I am considering purchasing a Bachmann, Baldwin 2-8-0 Consolidations, UP #724 .  However I understand that these locomotives use a belt drive that might be prone to slip or wear when compared to positive gear drives. 

One description that I found on the Internet mentions that is has an "idler gear box" yet the Bachmann official site indicates belt drive in the specifications.   Does this loco use a combination of both belt and gear drive?   Could someone please advise regarding the reliability and pulling strength of this model along with the actual as-built motor to driver wheel mechanism used.           PS. I have several gear driven Spectrum steam locos on my layout and they have been great products.