The MRX series pf Grip Shift controls are the Shimano compatible versions. If you get a micro friction front type then there's no specific click per shift and the der can be trimmed to avoid rub.

But there's a big difference in the ergonomics between the Grip Shift and the Shimano lever action shifters. I would hope you would ask your wife for her preference first

Unsure what "It takes about two fingers of slack in the first position of the little ring, just to make to the big ring." means. But as to the small-small rub, don't use that gear. It's the second worst as far as cross over, noise and wear goes. I generally suggest that when in the small ring one should avoid the last 2 or 3 smallest rear cogs. (Just as when in the big ring avoid the last couple of big cogs). Andy