I had the opportunity to test both the Night Train and the AC4, with their own respective cabs. After going through many amps over the years, both tube, solid state and hybrid, I just wanted to plonk my money down on a low wattage tube amp that can take high-gain pedals. I had that problem with my AC15 and AC30 where once I turned up the gain on my distortion pedals past 1 o'clock, they start to either squeal or shrill. I had an Epi Valve Jr head and cab that could take pedals but now I can't remember why I let it go.
Both amps, though belong in different classes of their own, are really impressive. Of course, like Faizal mentioned before, they cannot be compared with each other. But I figured since I rely on effects for my distortion needs anyway, I wasn't too concerned about the impressive gain on the NT, since it can't be activated with a footswitch. I was more concerned with a nice clean sound as a starting point. At $424 for the AV4HTV and V112 Cab, it was a steal!
Oh, and I don't know...I think the Night Train sounded better through the 2x12 V212BNX rather than it's own Celestion Green cab.