Here is a bit of interesting or boring info when mixing tyres.
Depending on how much into tyres you are.
I have currently mounted a Michelin Pilot Power single comp rear and a Pilot race medium front.
Lately I have been using BT 002's which are an excellent handling and gripping tyre if you play in the twisties and don't do anything else and last me about 3,000kms a set. (3 sets + 1 extra rear)
Now today I had a pretty hard ride with my younger friend on his '05 ZX6 636. On one particular section of tight winding steep road that I can do very fast I got a lot of squirming from the rear which I have never had from the previous 3 or 4 sets of PP's I have had.
I experienced this squirming twice (once going up and once going down)and backed off a bit, then it was ok again. It felt like the tyre was a bit flat which it was not.
Tyres were running 33 fnt and 36 rear.
When I got home I found the front is very balled up right to the edge and the rear PP is actually around the edge a little on both sides onto the side wall about 2mm and very worn looking but not balled up.
My conclusion is that if you have a race upfront which is grippier than the rear then you could over work the rear which I think I did, it was starting to feel a bit loose at the back, until I backed off.
So this is something that will not be new to those of you who race or do advanced track days, but I havent put this mix on the road and I probably won't do it again.
It didn't feel dangerous but it isn't confidence inspiring either.
My take on all of this bumph is maybe it is better to stick with the same compounds if you intend pushing the envelope a bit..... or expect to get the back loose a bit if you are going hard.
There you go for what it's worth.
DaveM
