Impressions & observations
So, it arrived & I installed in two days ago. A couple of things to note:
1) To move the HD to the OptiBay took a $75 adaptor from OWC. I guess there are cheaper ones out there, but I didn't want to mess around. The problem is that the optical drive uses a different SATA connector than the HD. It's a slightly more tricky job than a regular HD swap or whatever, but nothing too bad.
2) Remember to install your OS on the SSD before killing your optical drive! I didn't

.
3) I've got everything I use except the iPhoto library (200+ Gigs) and my iTunes library (100+ Gigs) and some rarely used user accounts on the SSD.
4) The HD still spins up quite a bit even when I boot off the SSD. Not sure why. Maybe spotlight. I know things like iStat access it. It didn't seem much more quiescent than before the SSD.
5) Using Disk Utility I "unmounted" the HD. Cool!!! It goes totally silent. The machine becomes still. Nothing breaks!!! except I can't use iPhoto or iTunes w/o going back to Disk Utility & clicking "mount". It's easy. I'd prefer a "mount/unmount" widget at the top (next to the battery indicator). Anyone know how to do that?
The machine is definitely snappier. In & out of Office apps used to be painfully slow; now it's a snap. Opening Mail with lots of re-open windows now flies. But the big thing for me is the stillness & quiet. Battery life seems the same.
Also, the back is substantially cooler. I no longer have to put a pillow or notebook on my lap!
Overall: A very good upgrade. I've dreamed of having a perfectly silent & still machine for years. Now I've got one!
btw, OWC lowered the price for Black Friday before mine arrived & they credited me $15 when I sent them a note about it. They're a good vendor.