Are cohesive gel butt implants better for active people who do yoga and heavy weight lifting?

Cohesive gel implants are definitely the better and more modern option.
The reason why there are not available yet in the US is the diligent,but yet slow and tedious process of FDA registration. But I believe they will be available soon.
I am totally convinced that once available most if not all my estimated US collegues will switch to cohesive gel. Just like it happened with cohesive breast implants which were likewise not available a long time due to FDA registration.
Solid implants are merely a so called class II device with no special registration requirements.
In theory, you can have them made in any hardware store. And if you want, yo may even declare them "patented" implants afterwards !Might help surgeon marketing, but does not solve the problem.
However,if you have a moderate sized solid implant you should be ok.just not too big.
I have read a few posts here were surgeons were promoting solid implants with highly dishonest and artificial justifications, beware of those. I submit they are merely saying this because they are forced to use them.
You can be sure that once the cohesive implants are available in the States, these guys will likely switch.
Hope that helps !

Cohesive silicone gel implants are not used in the US as they are not FDA approved.  Opt for solid silicone butt implants which are made of highly durable material that resists rupturing, spilling, and deflating. 
Kenneth Hughes, MD, ABPS Board Certified Plastic Surgeon
Los Angeles, CA

Unlike breast implants, silicone gel buttock implants are not FDA approved and thus not legal for buttock implantation in the USA. Because there is no company  currently running studies for FDA approval of silicon gel implants I do not anticipate that these type of implants will be available anytime soon, definitely not within the next five years.  I actually see about one patient a week that had gel implants done in another country and, although they looked a felt great at first, they are now seeking revision because the implants are either visible on top of the muscle and/or grossly deformed by flipping/rolling over, rotating, scar contracture and/or the implant has ruptured several years after placement leaving behind hardened scar tissue and migration of silicone liquid. The soft semi-solid silicone rubber implants used in the USA are much less likely to have these problems if placed correctly within the gluteus muscle AND are considered permanent implants because they cannot rupture and leak silicone gel. In 2015 I created and recently patented a new "Stanton Anatomic" shaped implant that avoids the unnatural effects of round implants, whether silicone gel or rubber . The benefit of this is the fact that ~95% of patients have much more of an oval shaped buttock cheek not round, thus a true oval implant (i.e. Stanton Anatomic implant) creates a much more natural and harmonious buttock contour. This is especially true when the patients bends over, does squats, or pokes their butt out while striking a pose or dancing. Many avid weightlifters, fitness competitors, and athletes from various sports have had these implants without problem of movement, visibility, or drooping.  Glad to be of help.