JK IS getting better. It's difficult to go in and take that place. JF is my favourite 'lead' guitar player...I tend to prefer anti-heroes like Cobain/Coxon and Marr, not flashy players, but JF is SO good at melody with solos, it is unreal.
JK is starting to get comfy and funky with them now, and it shows. He just needs more confidence, which will come. His backing vocals are picking up as well...a massive part of JF's presence in a band.
I've ALWAYS thought Flea sounds better with a bass with a sweet-spot humbucker. It just works. Underpins yet cuts, which is why I like Stingrays so much. His tone got lost with a Jazz....it just didn't bite.
Cool bass though. Why a company hasn't recently picked him up and made a big deal about a signature model is beyond me; he is one of the most famous modern bass players and a credit to bass in general.