Last time, I went from Sosua (where I picked some folks up) to Santo Domingo taking the Sabaneta-Jamao-Moca-La Vega mountain road. we saved about 30 minutes over the averages recorded from POP to La Vega over the tunnel-Santiago route!
The Moca mountain road is in pretty good shape for most parts. But it IS windy and narrow at times and one will encounter a few of the usual idiots montaos en una jeepta muy vacana who think they are cool to pass others from behind a bent they can't possible see you coming around. So go S L O W , keep your high beams on during daylight and a hand on the horn (in these situations, I kind'a like to keep a truck or something in front of me... bumper extensions, you know... keeps them happy too... they're primero!)
... J-D.