It's very difficult, if not impossible, to find a single banjo that's excellent for frailing AND bluegrass. I have a Deering Sierra bluegrass banjo that I used to use for frailing, and to get a good Old Time sound I had to take the resonator off and stuff some padding inside, behind the co-ordinator rods. With no resonator, the flange used to dig into my leg with 14 pounds behind it. I still have it, and one day I may try and learn some 3 finger picking, but my best banjo now is a Lo Gordon (Ceder Mountain Banjos) openback with a Brazilian Rosewood body and no metal tonering, which is light, manageable with a perfect sound for old time clawhammer. I would suggest that if you want to get GOOD, you decide which style you really want to play and go for it 100%, with a banjo that'll help, not hinder.
A good compromise could be a Wildwood, one of their openbacks with a tubaphone tonering - well made block rim and lots of volume you could use for bluegrass, but manageable, with a tone that would sound good for old time as well.
Good luck with it
Ray