so in the last couple months i've done two projects where the basics were cut on four track cassette.
pretty fun to work with that. they were for the little label i operate out of my house. one was for NC's stripmall ballads and one was for steve mannion's upcoming starvadinsky divinyl project. the sounds off those old machines is kinda grainy and warbly. i really like it. {i can imagine an LA producer guy paying lots of cash for a plug-in that does that haha!} the sound kind of reminds me of super 8mm film. kinda grainy and strange, and almost anything done with it already appears to be from some other time/place. although i'm biased and a fan of lo-fi obviously, i think it would be good if more bands/artists would work off four track. you kinda have to get creative right off the bat, and the components that make so many records sound exactly alike would be gone. here's an example: one of the best drum sounds you can get are a cool kit, in a cool room with one mic. just keep moving things around until it sounds great. easy enough, it just takes time and ears.
i kinda think in terms of "is it cool or not cool?" and not that whole "will this catch on???? will this not catch on???" thing, which means i'm probably not the best one to ask unless aesthetics is your thing! haha
i was in a band one time and we did a four track release to self-released cassette, and we probably made more money off that than anything we did, or very close to it. once we started messing with "deals" and all that, we got money up front to work with, but the income got chopped up moderately to severely to completely you see, and i don't think the profit margin of anything we did ever got better than that release. so much for economics.
as far as pure sound and vibe go, those old machines are pretty cool.