my current layout is quite unprototypical with a lot of 072 curves and steep grades. My 3rd Rail engines aren't happy in such an environment.
Jeff
If operating characteristics are a factor in your decision that should favor the MTH locomotive. I have put many miles on an MTH USRA light Mike with a drive train similar or identical to the L-1. It is good for 20+ modern plastic O scale freight cars (Atlas, Lionel, MTH, K-Line) on a 2.5 % grade with O-72+ curves.
This video shows the MTH USRA mike with 18 cars and a caboose pulling the hill through Spiral Tunnel.
http://www.youtube.com/watch?v=lIleIVxIC-M
Ed is right on the drawbar length. If the version you are considering has the wireless drawbar you can swap it out the for a shorter one. Since the 3 rail version of this locomotive is advertised for O-42 curves you should be able to go to a shorter drawbar on O-72.