Exchanging 350cc for 250cc Breast Implants with Minor Breast Lift?

Make sure you know exactly what the surgery entails.  It is fairly easy to determine how much native breast tissue you have, and how your likely postoperative appearance would be with a lift and smaller implant.  However the difference between the two sizes you mention is not huge, so do spend some time with your surgeon on this issue.
You don't want to have a surgery only to discover you are still top heavy and need further surgery.

Hard to say without seeing you.  Having said that, often when we down size implants there is extra skin.  This skin will sometimes need to be addressed with a lift.  Talk with your Plastic Surgeon about your expectations.  Bring in photos if you can.  I also would wait at least a year before doing revisional surgery.

Hi there-
The best advice I could give you is to focus on your desired breast contour.
Forget everything else.
Close your eyes and imagine the breast size, shape, and proportion to the rest of your body that you would like to achieve.
Now communicate that appearance to your surgeon. In my opinion, the best way to do this is through photos (that whole "picture is worth a thousand words" thing has been around a long time for a reason), but the point is really to communicate what you want to LOOK LIKE- NOT what number you want on your implants or what letter you want on your bra.
After understanding your desired APPEARANCE, your surgeon should be able to make a good recommendation for achieving it for you.
For more about how to properly proceed, and how not to, please read this:
http://orlandoplasticsurgery.blogspot.com/2010/01/achieving-beautiful-breasts-you-desire.html#f562 

The one question I would ask is how long you have had the implants? If they have been present for over a year the breast tissue has accomodated to the new volume and your skin will not tighten after the implants are removed. 350 cc are large and the impact on the breast and the skin will be obvious upon removal.
Generally speaking, when implants are removed the upper pole volume of the breast is dramatically reduced. The nipple position will appear lower and the breast will appear "saggy".
Like the surgeon you saw in consultation, I would encourage decreasing the volume of the implant not removing it. The exception would be if you have ample breast volume, you are young, it is within 3 months of implant placement or the skin quality is excellent and you are accepting of a more "mature appearance" of your breasts.
If you have saline implants and are committed to a surgical procedure, your surgeon may be willing to "pop" your implants. This will give you the closest approximation to your appearance if the implants were to be removed.
I hope this was helpful.

The real question here is: Are you that dissatisfied with your size that you prepared to go back to your original appearance? If yes, remove the implants and consider a lift. If not, a 250cc implant is a decent size decrease and will not differ tremendously from a 225 or 200cc implant. If you are considering smaller than 200cc you might as well remove them completely.

Whenever you downsize breast implants, you have the risk of your breasts appearing flatter or developing ptosis (hanging) of the breasts. So, if you downsize the implants, you should also consider a breast lift at the same time. Good luck.

It is very important to communicate your size goals with your surgeon.  In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or “C cup” or "fake looking" means different things to different people and therefore prove unhelpful.
Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup  size may also be inaccurate.
I use  intraoperative sizers and place the patient in the upright position to evaluate breast size. Use of these sizers also allow me to select the press implant profile (low, moderate, moderate plus, high-profile) that would most likely achieve the patient's goals. The patient's goal pictures are hanging on the wall, and allow for direct comparison.
I have found that this system is very helpful in improving the chances of achieving the patient's goals as consistently as possible.
By the way, the most common regret after this operation, is “I wish I was bigger”.
I hope this helps.

If you want to go smaller then more than likely you will need a lift. In most patients if you just remove the implants, they will look very flat.

If you have your implants removed, then your remaining breast volume will be similar to what you had prior to your breast augmentation, but you will have more sagging since your tissues have been somewhat stretched by the implants. If you would be happy with the breast volume you had previously, then you could consider removal of your implants and a mastopexy (breast lift).
Of course, a breast lift requires additional incisions on the breasts (usually around the areolar margins, perhaps up and down underneath the areolar margins, and sometimes in the crease lines of the breasts). If you downsize your implants, you may be happy with the new size. There will be some settling or sagging of your breasts with the change being somewhat uncertain.
You may need a lift or you might be happy with shape. If a lift is needed it can be done at the same time that the implants are changed out, or you might wish to consider deciding later whether a lift is needed. You might consider consulting with another plastic surgeon for a second opinion.

If breast augmentation is done for the right reason, few women ever look back, and in fact think little about their implants except at time for mammograms. The decision to have an augmentation should be made for self interest alone; the size and look should be of your making. It can be difficult not to be influenced by others, friends, spouse, boyfriend, even your surgeon, yet if the look is not you and you alone, how you feel inside, it is easy to understand why you might become unhappy with the implants.
When considering reducing the size of the implant, generally, it will take a reduction in implant size of 100cc to see a difference which is appreciable, better 150cc. If you are worried about still being top heavy perhaps you should remove them altogether. The mini lift may produce more breast scars and be another source of displeasure. You may just have the implants removed, a very simple procedure, and then you can decide if the breast shape is you or not. No matter how you look, if you feel right, and the look is you, happiness cannot be far off.
Best of luck.