The Allstar's volume distribution is ALL wrong for me. Difficult to use in the hole, and in flatwater. I love the M Rockstar. Everything is just as it should be in that boat.
But if you're going to go really hard in the boat... I know folks have been having trouble with the "kissing crack" that appears above the knee in the cockpit rim. Heavy use on the Rockstar has them popping up fast. If you're buying new though, the Jackson Warranty is the best in the biz, so they'll replace it. I bought a comp model used and got that exact crack in months. I have a buddy who goes through a standard model every 6 months or so (he is from Columbus, so he boats about every day. I also get a LOT of use out of my boats between flatwater, park and play, and SOME river running.)
My solution to the "kissing crack" was to buy a Jed. No regrets. I love it.