Can I run +p ammo through a lightweight model XSE? People have told me that the aluminum frame is less durable. They also tell me it will not last as long as a steel framed 1911 even with regular ammunition.  Is this true or crap?

It's true.  From what I understand a steady diet of +p ammo through a LW Commander will shorten the lifespan of the frame.

I have a 1985? vintage LW Commander.  It's round count is 25000? since I bought it in 1997.
The majority of ammo I've ran through my Commander is wimpy cast lead loads.  The rest is regular factory 230gr ammo.
I don't shoot +p or any warm ammo through it.  I've got an XD45 for the hot stuff.

Don't run +p ammo if you want the frame to last.  

Plus p on occasion ( no reason to run it regularly in any gun!) won't hurt it and I suspect it will last a very long time with regular ammo - not too many people shoot enough ammo to wear any gun out. Now if you shoot 300 rounds a week for ten years you may end up wearing it out!