Dave, you bring up a couple of good points that made me think... I too, am now using more 100 ISO and leaving the 400 to mostly "snapshot shooting". I too, have a few lenses that I look at and say- "MMmmm... should I sell this one that I haven't used in a while?" But then I think of the (sometimes) crapshoot of buying on eBay and worry that if I sell something and then down the road I realize I made a mistake, I'll never get a replacement in as nice condition.
Having said that, I do think of selling a couple of spare OM bodies that I obtained in a package deal with a lens or two that I needed. I'd much rather see the bodies exercised by someone than for me to never use them.