I guess they won't overpower a 4 x 4 room, being standmounters. So indeed, they might be a better bet than the KEFs. What stands will you be using, btw?
As for driving them with Colin's NCores: as you read in my post, I heard the Red100s, powered by a meaty Accuphase, and the result was very convincing. They have a very lively sound, but having a rather low sensitivity (86 dB or there about), they need some power to sound this lively. And so I feel the NC500 could make for a great match. Add the MDAC to this combo, and IMO you're up to a cracking system, with unbeatable value for money!
Having said that, a demo will tell you far more than the thoughts and impressions of a fellow forumite. Do you have a dealer nearby?
Keep us posted on the result. I for one am very curious how you'll end up!