Well, over the last few days I've stripped the beast and done a few bits and pieces. One of which was to replace the coolant with Evans. (For all of you that aren't aware I have previously done the CBR600 rad. cap conv. making my expansion tank an overflow tank so when the coolant got hot it would expand and push past rad. cap and into tank.)
I ran the bike until it was showing 100 deg. c and shut it off to check the level now that the thermostat had opened. The cap unscrewed with no pressure behind it and no coolant spraying everywhere I topped up the level, replaced the cap and ran it again for a while to represent being stuck in traffic. I removed the cap again aaaaaaaand......same result, no pressure, no coolant burning my hands.
Also the overflow tank is bone dry

...seems legit...

Evans coolant is popular with off-road riders, especially 4t owners, because its boiling point is much higher than ethylene glycol/water mixes. I use it in two of my dirt bikes, one 2t and one 4t. I should also use a fan, because they still get plenty hot, but it's still better to have hot coolant against a metal surface than no coolant (i.e, boiling). 907's have a fan, so this should be a good coolant to use.