I know what you mean about being in pain during the surgery. They always gave me more local but I could still always feel it- ouch! Do speak up, though, that it is hurting you

I went with the rechargeable units because the battery life is significantly longer (my Boston Scientifics can possibly last all the way up to 10 years), and I didn't want to have to have surgery every couple years to replace the battery. Also, the rechargeable units are actually smaller than the nonrechargeable ones, so it's a smaller thing inside of you. To be honest, there are days where I have issues with my charging or simply don't have time to sit for hours to charge where I start to regret choosing the rechargeable option. But all I have to do is think of how much longer the battery lasts and I'm ok.