I have done many go-arounds in a 737-300 full flight simulator and that includes from well below Vref. Have also simulated the Turkish Airlines 737 coupled approach at Amsterdam where the radio altimeter defect caused the thrust levers to close allowing the Vref to reduce to Vref minus 30. On that occasion the stab trim winds back a long way as the AP attempts to hold the ILS glide slope.
Providing the stab trim is toggled forward for a few seconds at the same time the GA commences and the aircraft pitches up because of the effect of GA thrust, the GA is relatively straight forward.
But if you are not up to scratch with a manual GA on instruments in IMC, especially if you are slow to operate the stab trim in conjunction with forward elevator to ease the stick forces as the pitch up occurs, then the pitch angle can quickly increase to a dangerous angle.
If the GA starts at an already slow airspeed well below VREF, then the trick is not to call for Flap 15 until passing VREF in the climb. Calling for Flap 15 at Vref minus 30 from a Flap 30/40 landing approach is most unwise as the aircraft will almost certainly stall. Treat the GA like a Windshear escape manoeuvre and don't touch the gear or flaps until the climb is safely under control and speed is beyond VREF and increasing slowly.