Personally, I don't believe this is an area pilots, outside of flight test programs, should be "experimenting" with. The main problem I immediately see is, "What happens if the experiment fails?" If the TKS fluid doesn't work as a de-ice in a particular set of conditions/airframe for some reason, now you're in a world of hurt. If an accident/incident were to happen, it will be difficult to explain to the company or FAA why you had a problem with several gallons of TKS remaining in the tanks.
I can't speak for 210s or Barons, but I know the SR22 flies like crap with ice on it. Being in a plane that flies like crap, and maybe not being able to make it stop flying like crap...no thanks, not for me.
The POH/AFM specifically states the system is to be used as an anti-icing measure. I don't know why the manufacturer wrote it this way, but I'm sure they had a reason. I don't see any reason to experiment with this any more than I'd care to experiment with red lines on various instruments.