XCR's for MX?

guys im currently running 20 inch XC's on the back of my 400EX. its getting time for some new tires and im planning on racing mx this year. im wanting smaller tires for mx but i also ride alot of trails. i was wondering how a set of those new XCR's would work for mx racing. i was told they are smaller than the XC's which to me were too big. but i still used them. i really didnt want to buy two sets of tires, but if i have to i will. if i do go with the XCR's as an all purpose trail/track tire im still undecided on which front tire size to run. im still running my bald stockers up front at the moment. any help would be apprechiated

come on people, anybody that has them or anybody that races alot should be able to help me out here... i need suggestions

[Moto92]

The XCRs smallest size is still a 20'' tire. The only way to go any smaller is to get the MX which are 18''. The MX are a soft compond and only two ply rating, not to good for woods.
You can have two sets, the 18s for the MX track and 20s for woods and XC, thats what Im doing.

[Blackguywithouta400]

I just put the new XCR's on my quad and i love them, i ran my last MX race on them and they worked great i was able to get a holeshot and slide very well through the tight corners. I really like the new tires i think they transition very well from straight to cornering, and I never felt like it was going to spin out, i would recomend them 100% You will notice they are not true 20x11x9 they are more like 19.75x10x9 narrow tire like a stock one but very square. GET THE 20's there great

ok im convinced. thanks for the input!