What are cons of not using a cell saver for BBL?

I have not found cell saver to be necessary or useful in these procedures.  The surgery can be shortened or the number of procedures reduced.

If you are a good candidate for a Brazilian Butt Lift (BBL), the optimal outcomes are achieved with: 1) use of VASER liposuction to harvest the fat, 2) a closed looped system such as Puregraft to process the fat, and 3) strategic micro-packet transplant technique. These three processes have demonstrated over 95% fat graft take. This means that your results will be stable as long as you maintain your weight. As an official VASER trainer, I am routinely referred unhappy BBL patients. One of the most common reasons for disgruntled BBL patients is that patients are not able to accurately communicate their desired buttocks goals to their surgeons.  A buttocks assessment tool can be an invaluable tool to communicate to your surgeon the exact buttocks size and shape you are desiring. A Skype or FaceTime consultation with a BBL specialist can help you get an accurate recommendation and pricing. 
Respectfully,
Arian Mowlavi MD,FACS
Realself 100 Hall of Fame Inductee

The number one way to decrease blood loss with Liposuction with or without fat transfer is to inject appropriate amounts of Tumescent solution and letting that solution take affect before surgery which takes 20 minutes.
Plastic surgeons who do liposuction under general anesthesia are often under time constraints to get the procedure done and often don’t focus enough time and effort on injecting tumescent solution.
The solution contains a drug called epinephrine which constrict blood vessels making blood loss far less during this procedure.
It takes 15 to 20 minutes for epinephrine to work fully.
Most plastic surgeons are not willing to sit and wait that amount of time. Properly injecting this solution and waiting 20 minutes is often seen as a waste of time since the patient is under general anesthesia and operating room time is expensive. there are also incentives to not keep the patient under general anesthesia for longer than needed.
I perform Liposuction and fat transfer with patients awake. This requires every area to have ample amounts of tumescent solution placed and giving it sufficient time. If not the patient will not be comfortable through the procedure. For me blood loss has never been an issue.None  of my 7000 Liposuction cases has needed or come close to needing a blood transfusion.
Surgical technique is the way to minimize blood loss with this procedure not the use of a cell saver.
When good surgical technique is used you don’t need a cell saver because blood loss is a minimum.
Surgeons who move too fast or don’t focus enough effort placing appropriate amounts of tumescent solution will have increased blood loss. 
Even then, blood transfusions are fairly rare.
The drawback to not having a cell saver is that your own blood cannot be transfused back into your body.
The advantage to not using a cell saver is cost savings and you will not get an auto blood transfusion. 
Good surgical technique for this procedure illuminates the need for a cell saver.
I would venture to say that 100% of surgeons who do awake Liposuction would agree with my assessment.
Best, 
Mats Hagstrom MD