I use one of the pellet pistols designed to look like a Colt Python.
Works for me to help maintain eye / hand coordination and trigger pull.
I've not found any noticeable negatives from practicing with it. Does it transfer directly to firing a .44 mag? No, because there's no noticeable recoil. But if I use only that as the benchmark, then practicing with my .22 Buckmark would serve no purpose either.
It's all practice, weapons manipulation in some form, and IMO, worth the time and effort. Ya just have to ignore those aspects that don't transfer across and retain those aspects that do.