The problems with SL are mostly upgrades, that's what I presume, since I've not seen anyone complaining who has actually done a complete and proper clean install.
I upgraded to SL from 10.5.8, not one problem. Applications boot ever so slightly faster, I enjoy the improvements. The graphical glitches are still there, but they will probably be fixed in 10.6.2 and don't effect anything (at least the ones I've seen)
I then did a clean install on a new SSD, identical results, although I did have trouble ejecting the DVD after being installed!
Funny that that happened on the clean install! (it was resolved by restarting & installing 10.6.1, I'm not sure which fixed it)
If you do a clean install, erasing everything on your hard drive that you're installing to, so it's a brand new OS with no data on it, you should be right.
You just transfer the files you want over.
I've used Time Machine to transfer a few files I think, but mostly I dropped everything I needed on an EXT. HD and just dragged it over.
Migrating from a HD or installing from Time Machine is not a clean install.
I have noticed that from time to time, when shutting down I get the blue screen for a little too long, on the SSD that's 5-15 seconds, on the HD it was about 20-30, but it is very infrequent.
Kind Regards