Planars - yes, fantastic tone, pace, resolution. Not so great - LF, and the sensation of listening to headphones - keep your head still or you'll fall out of the sweet spot. Also only Quad ever made really authentic sounding planars, imo.
Open baffles have their own acoustic issues, but I'm not that familiar with them so won't comment too much.
The thing about the Nautilus and the entire Vivid range is that the care taken with the baffle shape results in a larger sweet spot where frequency response is even, so more people can enjoy the music. The vertical dispersion advantage is also there - you can enjoy music sitting, standing or even relaxing on the floor (provided you have a nice soft rug, that is)... So many advantages to a Vivid cabinet then, but generally the public remain steadfastly accepting of "wooden box theory" norms and ignore the problems that Laurence Dickie has identified. Me, I don't get it...
As for the 800 series, beautifully made for sure, but are they really that much different (aesthetically only, of course) from Dickie's designs? I mean, a tube mounted on a blob mounted on a curvy wooden box topped with leather? Not exactly conventional, so why do people automatically rate it? I mean, have you actually listened to any 800 series?