I loved my A36 -- responsive, roomy, fast, and just a lovely coast-to-coast or touch-and-go airplane. I'd have one again today in a heartbeat if I could afford it (I had deeper-pocketed partner then). But it demanded pretty steady attention to hand-fly IFR (or VFR, for that matter), and I'd often snap back to reality and find myself 100-200 feet off altitude and/or 10-30 deg off course. I figured that was the price of the lovely fingertip flying feel, and I never minded, or turned on the autopilot much. Like anything, you get better as you go, and my deviations got smaller and less frequent over time, though it would still bite me if my attention wandered.
My C-182, by comparison, is a bit of a truck, though I love it almost as much. It doesn't seem to wander quite as much or as quickly as the Beech, so my impression is that that makes it a more stable IFR platform. This is utterly subjective, of course, but the 182 seems a little more stable than a 172 I flew right seat in a lot, maybe because it's heavier. Or maybe because it has so much more elbow room than the 172 I ascribe other good qualities to it as well.
