It's definitely feasible, i win with it all of the time, you just need to be prepared to play at least a 40 min game and then get flamed at the end of it. Mech as the transition in is safer, bio into skyterran only works on very large maps, but it is faster, and the bio gives you a better chance of denying him from taking absolutely the entire map. No pro's that i know of go bio->ravens, but it works on huge maps (alterzim and sorta frost) i do know though that bomber did it way back in WoL on metropolis and had an epic game vs some zerg. things have changed now with the different seeker missle, but it was still what inspired my current playstyle