I've seen a coupe of folkies use the Bose L1 system which is an integrated bass bin with a tower and clever software. Bob Fox, for one. Great sound, very portable. Not cheap, mind! See Bose L1. Fishman do a similar one, too. Both have been very favourably reviewed in Acoustic magazine.

I still use a couple of AER Compact 60s. They're great. Only two channels, but easy enough to splice on a mini mixer if you need a couple more.