Re: Grover Keys.. 18:1 vs normal
Anything over 12:1 or 14:1 is just a waste of time turning keys in my opinion. No advantage in tuning stability, and there's nothing to prevent you from reaching the same "precision" with a 12:1 tuner than you could with a 40:1. The gear ratio just isn't the weak link in the chain here.
That said, the Grover 18:1 Statites are nice, very well made tuners, and pretty cheaply priced. If I could find someone making a nice 14:1 set I'd be thrilled, but 16:1 seems about as low as can be found in most quality modern tuner styles.
As to which tuners to keep, Grover makes and has made a lot of different styles of tuners, and I have no idea which styles in particular you are referring to. There are some that are better than others, but gear ratio alone is not really the deciding factor.