Andy,  I have been playing the prov 1 x for years and have always found them to be the best.  However, the new 2011 version seems to be harder.  I can't say that they are longer because the weather has been so cold.  At present I am considering going to the prov 1 and hoping that they perform.

Has anyone else played the prov1x and experienced this? 

I've only gotten to play 9 holes with each, but they're performance is pretty much the same.  I found a little less spin off the tee, but as for the short irons, chips, and pitches they play pretty much the same.  We'll have to see when I actually get to play in some good weather.  I like to play a round with both balls playing two balls on each hole, or having a little self scramble and seeing which ball performs better on a majority of shots.  It's still up in the air for me.  I've always been a Pro V1 guy, but this go around, both balls played equally nice.