I have Tron an xm LE and I believe Tron is far better. I have not played XM pro but just the LE.
Now the code of XM is getting better but Tron is just so much more fun to me, I enjoy Tron more I think because its more easy, I mean the modes in XM such as Magneto, Weapon X and all the villains are so much work.
Tron seems to be more fun and I could play the multiballs over and over not groan like when I have to play Weapon X over and over.
Some might call Tron too shallow, but not for me, I am not a great player and enjoy the fact that I can play a quick game and still have fun.
My ball times on XM is almost twice as long as Tron.
If you enjoy longer modes and tons of work to get to the wizards might like XM better, but for me Tron is more fun, and for me much easier to hit most of the shots, while XM seems too tight on many of the shots.