Bought a Speck See Thru for my new MBP 2010. Apparently they'd just nicked out the extra plastic near the magsafe connector...
And yesterday when I tried to remove the case for the weekly clean up, I broke one of the hook holding the lower case...Long story short, I went out and got an Incase Hardshell(Black) today. I put it on just now, it fits great. Unlike Speck, they didn't cut out the extra plastic, the lower part seems to be newly built. But material-wise, I think speck has thicker plastic

Incase has slimmer plastic.(Incase's feels slightly slimmer in my hand) But the hooks on the Incase's seems to be built better, they feel tougher
My suggestion, buy both and return the one that you don't like