I have been using the 305 G-Claron on 8x10 for four months or so. It is similar in size to a 210 f5.6.
To my eyes the G-Claron is very sharp. It is not too big for me, and has so much coverage that it has not even been a consideration for me when making movements, a real luxury. I let the lensboard rise and fall at will. I like the modern shutter, especially when shooting fast film like HP5+. I also considered the 12" Dagor, as I use a 9-1/2" Dagor mounted in a shutter, also excellent.
With the G-Claron, I definitely notice flare in situations where the light has a low angle of reflectance, such as photographing down at a sandy beach, with the sun beyond. Or on a highly specular day with the light bouncing all over, off of the clouds and everything else. I don't know how much better a multi-coated lens would be at handling this, however.