Is 400cc round silicone too high? Negatives to that size? Will I be able to achieve my desired fullness? (photos)

Thank you for your question and photographs.  You are an excellent candidate for a breast augmentation, and a size/shape similar to your goal photographs can be obtained. Though an in-person examination is required to give you the best implant size, style, and profile recommendation, the concern of the surgeons recommending a smaller implant lies in the fact that larger implants have increased risks of implant malposition and bottoming out.  I would continue to communicate with your surgeons, and select the one with whom you feel most comfortable, and who best understands your desired goal look. 

Thank you for the question and pictures. Based on your photographs, I think that you are starting at a good place and should have a very nice outcome with breast augmentation surgery.  I also think that your goal photographs are realistic.

Generally speaking, the best online advice I can give to ladies who are considering breast augmentation surgery (regarding breast implant type/size/profile selection) is:

1. Concentrate on choosing your plastic surgeon carefully. Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you are looking for. Ask to see lots of examples of his/her work.
2. Have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining breast implant size/type/profile will most likely help achieve your goals.
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. In bra sizers can be useful communication tools also. I have found that the use of words such as “natural” or "C or D cup" etc 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. The use of computer imaging may be very helpful during the communication process.
3. Once you feel you have communicated your goals clearly, allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals. Again, in my practice, this decision is usually made during surgery ( after the use of temporary intraoperative sizers).
I hope this, and the attached link (dedicated to breast augmentation surgery concerns), helps.

Best wishes for an outcome that you will be very pleased with.