Last summer I had an E10 front with an E07 Dakar rear. The rear was quite a hard compound and soon got pretty slippy in the wet, had a few moments on it. Might not be as bad on the non dakar version. It didn't take long with road and offroad riding for the E07 rear to wear down enough to get to the solid centre strip, which had its pros and cons. I think once on the solid centre strip it was actually more slippy on road and also far less driving traction offroad, but it did slow down the wear rate considerably.
Every time I've looked at buying tyres all the big suppliers like tyreleader seem dodgy in some way.
I got my Mitas tyres direct from
http://www.mitas.co.uk/ and I think that's got to be the best option if they have the stock you want.
Think this summer I will go E10 front and back.
Just noticed how old the original post is, despite being one of the most recently active threads in here, hopefully this might be of use to someone anyway.