I would guess most of the matchers now will no longer continue with the GP4300, but instead invest in the newer GP4600.
I do have to say I have some of the IB 4200's and despite being only 7 charges old, I have had 2 cells fail (Luckily Nick at Demon is happy to supply individual cells with appropriate numbers
). I have never encountered a failure with any other type of cell before (including gp4300), and I'd like to think I know how to treat them correctly.