We go through a few C-210's as dealers, and always have 1 "in stock" for business flying - although I only have 40 odd hours in C210's - so not a lot of experience yet.
Still the best load hauler and solid in the air - but also only done decent length tar to tar runway flights so far, unless with my instructor along for shorter strips.
Best "mod" that I learnt in a little cheapie Cherokee, was to have a sheepskin seat cover on the front seats.
Doesn't stop you sweating, but does stop your sliding around on hot leather seats with a wet arse
If all the big machine drivers in Airbus, Beech, Boeings, etc fly with dead sheep's clothes on their seats -there must be some benefits to the solution.
For what it's worth - my butt certainly thinks so !!
See our current T-210N in her new paint job - looking very cool and a solid 160++ Knot machine