I'd ride it like that.
My only concern would be if the rear was the grippier tyre, because I expect from a matched pair that the back would start to get squirmy and give a few warnings before the front let go.
If you've got a better rear than front you might find that the first warning you get is your elbow on the deck, shortly followed by the rest of you.....
But as long as you're not trying to go for a local roundabout lap record, or track days you'll be fine.
As regards insurance, I can't see that they would be able to hold back payment on different tyre makes- as long as both makes/sizes and speed ratings are recommended for your bike.
After all, they can't apply it to cars- are you going to change the other three tyres as well if one has a puncture and isn't repairable?
Lastly, you'll be getting used to it for a while, and probably won't find its limits for a few weeks yet, by which time you'll have bought a much stickier pair of track-day-only's, a race exhaust, replacement shock and fork upgrade, tiny plate, DB Titanium screen, HID conversion, carbon everything and anodised bolt set, Rossi paint job, polished wheels, grips with tassles, etc, etc, etc, etc.....
Your insurance company won't recognise the bike anyway
It's not falling off, it's an upgrade opportunity.
would it be noticeable in normal road riding 
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