What a nice surprise to be away for awhile and find this thread! Hey, dwditty, thanks for the post. Nice to know someone notices. Now, about New England bluegrass bands. The Boston Bluegrass Union maintains a fine site with lots of listings of regional bands:   

http://www.bbu.org/Band_List.htm

And as for bands in the past, Joe Val of course, but also the Lilly Brothers with Don Stover, who came from elsewhere (West VA?) but played at the Hillbilly Ranch in Boston for decades and have plenty of recordings still available.