) Most of which was motorway (200 miles each way averaging 70 - 100mph) Used about 900ml of oil (just topped it up to measure). Sounds like if I'd have gone on the NSR I'd have needed a Silkolene tanker following me 
The 3XV tank only looked about 2 thirds empty though, so maybe it's a bigger tank and this makes the NSR consumption feel so much worse to me as I'm topping up more often? What's the volume of the 2t tank on a 21? Anyone know?
Having said that, your figure of 700ml in 210 miles sounds just plain mad - if your figures are right, the NSR uses more than 3 times as much oil as a bike with twice the cylinders (the 500) and 7 times as much as a comparable twin cylinder bike (the RGV). Where the hell is it all going? Using my figures, the 3XV would've used about 300ml for your journey. Tho' as mine was prob a much higher average speed due to the 400 + m/way miles, we could prob drop quite a bit off that; but I doubt it would've dropped down to 100 ml. All of which suggests that it's the little Suzuki that's the most frugal. Obviously these are not like for like comparisons (diff riding styles, road types etc) but it is quite illuminating all the same. Thanks for going to the trouble to measure.
BTW - the racing at Oliver's mount is mad isn't it? - used to go a lot when I lived in Hull. Have you ever done a few laps of the 'circuit' when it's quiet up there? Quite how anyone has the 'nads to race around there is entirely beyond me. Heroes or fruitcakes, I can't work out which
Cheers
Wb