Switching from saline to silicone gel implants can decrease rippling, but each person needs to be treated individually. Rippling can happen in front of and behind the muscle, but it is more likely in front of the muscle. Sometimes changing the implant position is more important than the type of implant.
If your rippling is due to capsular contracture, releasing the contracture may help. If your rippling is because you are very thin, and there is not enough soft tissue to disguise the contours of the implant, then moving to behind the muscle makes more sense.
When the implant is behind the muscle, the outer edge is not completely covered, so rippling can occur in this area. When the implant is in front of the muscle, rippling is more easily seen over the entire breast.
Unfortunately, I cannot give you any specific advice via this forum; however, if you are uncertain how to proceed, it is worthwhile discussing your options again with your plastic surgeon, and you might consider getting a second opinion via an in person consultation. Thanks for your question.