if you have the money go for the 140SR for sure. I have a XR140 pitpro and alot of the mods and upgrades I have done on my bike I have noticed are things the 140SR has standard. For the price of a XR140 + mods to try bring it up to the same level as the 140SR you could of had the SR to begin with and spent alot less time spinning spanners and more time riding.
Don't forget Ken and Linda at MSO will do you a special price if you let them know your from miniriders.