The problem with the 2007 BaneBots gearboxes was due to an (apparently) brittle carrier plate. Those with a hardened carrier plate can be identified with "-HC" at the end of their part number sticker. That said, plenty of teams used the gearboxes without any issues that year (especially if you support the end of the shaft with a bearing rather than cantilevering the load).
Other planetary gearboxes that fit the CIM include:
-Banebots P80 series (
http://banebots.com/c/P80A-nnnn-n0n5)
(14 reductions between 3:1 and 256:1)
-AndyMark GEM500 (
http://andymark.biz/am-0270.html)
(Each level is a 3.67:1 reduction; you can stack as many levels as you want for more reduction)