Have you thought of doing a single larger cylinder between the two modules a la
Blue Cheese. Might be less parts and less weight.
What is your gearing for each wheel shaft in the pods from the CIM?
Are you concerned about deflection when the mecanums are down? Seems like a much longer moment arm around the rotation axle. I have wondered this for all the octocanum designs I have seen on CD. It seems like you would want to support the end of the axle that the pod rotates around with a bearing and have an external frame rail running the length. Perhaps the plate between the two pods is enough. Have you tried stacking weight on it to get the bot to 150 pounds?
Love the FIRST logo in the frame =)
-matto-