From what I've read, Vox think that it is indeed a sort-of direct equivalent. I'm not sure if it's catching on, though.
Recently, I purchased an MVX150C1 (Nutubes in preamp and power amp) but I think they're discontinued; the one I got was the last in stock at PMT and at a discounted price. I've not had chance to try it at a jam, gig or rehearsal yet but the tone seems good to me and I'd guess that it would be loud enough (150W class D 1x12"). Whilst they were generally available they didn't appear to be very popular, as far as I can tell.
I've also got a VX50 GTV (Nutube in the preamp) and this has proven to be loud for its size and very portable.