Shouldn't feel at all sluggish - the 1000 is very quick at real road speeds, it picks up at low speeds and flies when asked - as any decent 1000cc V-Twin should. And it should feel very muscular compared to the Divvie 600.
Having said that, if you are bimbling along at around 60 in top gear it will feel awful - top gear is a very tall overdrive for motorway/fast cruising economy.
It will feel different to the Divvie, a 4cyl 600 = lots of revs everywhere to make progress, the V twin will lope along on comparatively lower revs riding the wave of torque, typically sitting around 3-4500rpm unless you are [s:1tld99jz]having fun[/s:1tld99jz] making progress.
It should never stall, or misfire or pop on the overrun with stock exhausts and the inlet tract sealed up tight. I still think all is not right with the inlet boots, that would give erratic idle, popping and farting, but on mine, the rear was almost right off and it still went like the clappers - so it doesn't fit the sluggish/Got to rev it issue, TPS maybe?
Smooth...well, not always smooooth, it is a V-twin & lets you know it. My Pan is Smoooth like silk.
Its a pity you are so far away, it would be good to have an look at it/hear it to see what's been done to it.