I gave it a go using Wayne's Expandora (II?) clone and my gig KE2. Got good results up to fairly high gain levels as well as mid-gain. Definitely makes me more confident that I'll have gain options beyond what's on-board which really isn't even accessible when gigging due to lack of channel switching.
So far I haven't had a huge amount of luck with the EF86 side - I think it would be good for some specific studio applications, but I have a hard time imagining doing a gig in that mode. Of course it's switchable, but there's a big volume difference (EF86 > 12AX7) so I'd have to dedicate the 2nd MV to compensate, or else run a volume pedal in the loop.