ill look into this more, ive just been having some good success using the make DESTDIR=... install, ive recompiled most my apps, and its working well. i ahve heard of reports of it not working with all apps though...
i did have a go at mounting usr/local but what is the command to mount a directory rather than a block device ??
also in summary of the question of this thread, id say i have to prefer /usr/local, as i started out think usr for some time because it meant less typing for one thing !! but now i like /usr/local more as most apps install with that as "prefix" by default, and lets you keep/see your own additions seperate to what ever came with your OS/ROM .