I'm finding the whole SFS thing rather confusion. I swear that I was using a 2.x version where I was previously using a 1.x version. Or maybe I went from SFS1 to SFS2. Sheesh, I dunno. I'll have to fire up the 4000 to find out for certain.
But as far as usability, I have been using SFS for many many moons on my DH1 partition which houses all of my Internet utilities such as YAM, AWeb, etc. I've only recently been using IBrowse, but not heavily. YAM certainly seemed to beat the crap out of the drive and SFS is CONSIDERABLY faster than FFS handling my email, especially when moving or deleting messages.
I have never had an SFS problem. So, maybe I fall under the lucky category. It's been with me as far back as I can remember, back to my A530-powered 500, 4040 A4000D, and CSMKIII A4000D. Mind you, I've also never used IDE drives, so maybe that helps?