Ok, with 2 gigs under the belt I can now report in more detail on the SVT-7 Pro.
On Friday night I ran it into a mini stack of two SWR Goliath Jr 210 cabs at a tiny little pub gig. I didn't need a lot of volume in this room (vocal PA only), however the SVT-7 had that nice reassuring Ampeg fatness happening, with some noticeable inherent compression even with the onboard compression dialled off. The tube preamp in this head is warm and sounds very natural and tubey at gig volume. I'm not convinced that the claimed 1000 watts output is any louder than my 800w Markbass LM800, based on where I had the master volume on the Ampeg compared to where I would have the master on the LM800.
On Saturday night we played a medium sized club auditorium, although again we only went with vocals (and keyboards) into the PA. I brought the Markbass CL152 sealed 2x15 cab this time. Wow, this is a match made in heaven! Into the 215 cab the SVT-7 Pro sounded lovely and creamy, just like all my favourite rock albums from the 1970s. Again, even without PA support the SVT-7 had more than enough in reserve, I had the gain around 9 o'clock, and the master just past 12 o'clock, so it was just cruising along nicely.
Originally I was going to make a decision and sell either the LM800 or the SVT-7 Pro once I'd worked out which one I prefer, however I think I'm going to keep both of these. Why? Because the Ampeg is not as portable as the LM800. It's not much heavier really, at 12lb vs 6lb, but it is physically larger, and without the rack ears and front handles fitted the Ampeg feels a bit like picking up a wet cake of soap, so it's not as simple to pull out of a bag and sit on top of your cab/s as the Markbass or other lunch box amps are. I'll keep the Markbass for blues gigs and rehearsals etc when I want to travel *very* light, and I've already racked the Ampeg into a brand new 2RU case.