I've got 4 packs of the 4800 saddles.
Had them since start of year and used them in my and my son's 2WD with 7.5t motors and in a 4WD with a 6.5T. They get used and charged upto 3 times a day each often charging them straight after a race. Absolutely zero swelling on any of them and never had issue with lack of power/punch.
I'll run them until the start of next season and then probably replace them with new ones although probably not really necessary.
At under £100 for 4 sets I really can't fault them. I just cannot justify spend £70-80 a pack when I cannot see how they will get me around the track any quicker.
I guess a really top driver might notice some difference in punch/power but if I needed more of these I'd adjust my speedo or motor up. Never been at a race meeting when I could not have more power than I could control
Rob