I've spent plenty of time on both games and enjoy each of them for different reasons. They offer contrasting play styles which are hard to compare. One is brutal, out of control, and shallow. The other is smooth, flowing, and deep(er). You can't go wrong either way, but I voted with my dollars and bought an IM VE.
Part of the reason I didn't pull the trigger on ST is that I was torn between the costs & benefits of the Pro & LE editions, ultimately choosing nether. Option paralysis, perhaps? There's only one IM, and it's great. (Yes, I know the original IM and VE are different, but they're very close. Definitely not a Pro vs. LE situation.)