I've used two machine for my TF servers. An SE/30 8/500 and a Mac II 20/2000 with a Daystar 040.
The SE/30 had ramdoubler and wouldn't only last a few days before something went wrong, whereas the Mac II goes on for weeks and only breaks when I play with it :-) So, I would be careful and test the system with and without RamDoubler before leaving it alone.
