i tried the v-twin pedal and it didn't sound anything like the rectifer does, nor for metal.
the JT-valve boy does sound very nice, but i'd have to give a try for myself.
from mesa boogies site:
Single rectifier: 50 Watts, Class A/B Power / 2x6L6, 5x12AX7
Duel rectifier: 100 Watts, Class A/B Power / 4x6L6, 5x12AX7, 2x5U4
Triple rectifier: 150 Watts, Class A/B Power / 6x6L6, 5x12AX7, 3x5U4