Anyway, despite how it may seem, I actually do like OS4.x, I just wanted to be honest here as a lot of the answers you'll get will be written with an air of bias, and truths twisted because of it.
Yes I am in the same camp on this one I own a sam440ep and am very happy with it (I just wish the would fix USB to be usable for more than attaching a keyboard and mouse) on an hours or use for price paid perspective I have had value for money out of mine, but it is an expensive solution that is not for everyone.
As a silent small form factor computer for playing back music, running Photogenics, ImageFX and use as an rdesktop client it works very well for me, but if what you really want to do is play ECS or AGA games there are better solutions at present.
If you want a games solution to play OCS and ECS games then the Minimig is my preferred option even though I still own 2 A500 and 2 A1200 (one expanded tower system and an 030 equipped desktop) as all you need to do is turn it on and play rather than try and get it working then play.
I may upgrade to a FPGA Replay board when they become more widely available and sell off one of my A1200 but at this stage I don't have the free cash and most of the games I like best run on an ECS system anyway.
Lotus 1 & 2, Civilization, Settlers, Pinball Fantasies, Eye of the Beholder 1 & 2 New Zealand story, Utopia, Rail Road tycoon and many others all run perfectly on my Minimigs. Lotus 2 even works in serial link up between my 2 Minimigs or 1 Minimig and an A500 for some serious multi player fun what else can you ask for in A500/A600 clone :-)