Which REs did you buy and why?
I ended up taking the plunge on the Softube FET compressor. I bought an expensive mic a while back and lacking any decent hardware compression options (none, rather), I thought I'd try it out. I wasn't expecting to hear much of a difference with the Reason stock, but it seemed to warm and tighten things up in a surprisingly pleasant way. I like the parallel knob, and it seems to take kindly to most tweaking - it's not hard to get good sounds out of.
So my money is spent, but I'd love to hear how other users are fairing... Did anything surprise you? What should we save up for?