So, the short answer is: visual inheritance in .Net *kind of* works, but pretty much useless. :) No, it does work, you just have to write some code in the subclass...
Bottom line, you can get to a situation where you can build your subclassed controls, get them into your toolbox, drop them on forms or other containers...and then modify your subclass to use a different color/font/etc, and have it cascade through.
But as you've seen, you have to do it the right way from the beginning, or you find yourself doing some back-peddling.
Kevin