If I was predominately single seat touring I would go with a 600ish bike. Probably an 690 with a larger tank and fairing. I have done about 100,000ks since April last year on a 950 and 990 across all sorts of stuff. At the moment I am doing the TCAT solo - I got stuck (as in needed to find someone to help) last week crossing some stuff I wouldn't think twice about on a 690, a flat front on a gravel road saw me down the road, wouldn't likely not have happened on a 690.
But I travel mostly with my wife and can ride a 990 loaded, two-up down gravel roads at 100km/h + all day long even 120-140 is generally not a problem. Also I can still spin the back wheel at 130 on gravel and get it sideways with a 990 - I would struggle to do that on 690.