I have about 500 jumps on sub 1.0 loading on old-style square mains (in those days canopies were bigger and I was lighter). Maybe it was because they weren't zero-P, but I never felt unstable, and the controllability and accuracy of the square were also superior to the round I'd been jumping before that. I have another 1600 or so on modern canopies at loadings up to about 1.4, so I do have some basis for comparison.
I understand the desire to downsize even if you don't want to swoop -- I did sell my perfectly-good old main and get a 150, and eventually go to a 135 for quite awhile. If nothing else, doing FS, I didn't want to be either the first or the last one down every.single.time. Not to mention the gear is lighter etc.
I've felt turbulence just as bad under the smaller canopies as larger ones. That might just be me, though.
Wendy P.