I have the Size Matters one, but am generally too lazy to use it every day to notice a difference in size, plus I'm not on T so I'd guess I wouldn't see too much size increase anyway.
It works, though, fo sho
It makes my clit sooooooooo much bigger, depending on how long I left the pump on, how much pressure was used, etc. Time it stayed big also varied, too, based on those factors.
I think it was 100% worth it because it really did work/ created an interesting hot/good feeling (hot literally and metaphorically), but I somewhat regret the purchase because I've heard you can make DIY ones, too, via I think syringes??????
I don't know why people say clit pumps are scary. Whenever I tell them about mine that's their reaction. The little pressure gauge on the Size Matters one doesn't work, btw. I was warned about it when I bought it--- that it's mostly just for show, and I believe it.