I never owned nor tried the G20, but I hear good things about'em,
if they're anything like the G10 I used to own, I'd say go for it.
the G10's really served me well for over 30 levels,
I imagin the G20's will do that even better.
if you can wait for'em, I'd say hold on for the G20.
about meter speed..., emm..
moving to faster meter speeds can be scary,
but if you don't let that bother you,
you can sort it out after a few practice rounds,
with time the new speed becomes natural,
so don't worry too much about that,
the extra yardage, spin, and trajectory is what you want to be looking for.
gl ;)