So I bought a Sam and in my opinion it was a major step back compared to the a fully tweaked 3.9 setup.
"Fully tweaked" is the key thing here... How does OS4 compare to a plain OS3.9 install? And don't forget OS4.1 has addressed many of the issues users found with 4.0. If you don't have the hardware to run 4.x, then 3.9 is fine, great even, but since I got my A1 many years ago I can honestly say my pimped out A1200 tower gets turned on less than once a month. I use a wedge A1200 with an 030 for my classic gaming needs, and OS4.1 runs everything else. AROS will be a good alternative some day but it's not quite there yet. And I'll probably give MOS a go if/when it supports my G5 tower or my G4 iBook.