I'm new to stick radios, I have a Code CR151 and understand it's a entry level radio. I now feel ready to upgrade my equipment, and would like to know how the following radios compare; (Futaba 4GRS, KO Propo Esprit IV, Sanwa Exzes-Z).

I will be borrowed a 4GRS for general stick radio testing during a race weekend in a few weeks. Its owner prefers his older KO Propo Esprit III over the 4GRS, which is based on Futaba's mid-level T4PLS. I skimmed through the Esprit IV manual, and it has some really nice details. If I manage to drive well with the 4GRS, I will probably go for a Esprit IV. My Futaba 4PKS-R is a great radio, but no matter whether I use it left or right-handed, something always feels odd.
In terms of quality, the Exzes-Z will also be a great top-level radio, but I'd go with KO Propo. Too bad Futaba don't offer a top-level stick radio, it is the attention to detail that matters for me.