We went with single speed, 2 stage transmissions, and they have worked great on our competition robot as well as our practice bot. The only comments I have about Vexpro are:
The plastic transmission housings when we got them early in the season did not give good gear interface and were noisy. We immediately decided to make our own plates and spacers, and they have worked great. Nice and smooth, and no discernible wear on the gears.
The lack of sufficient inventory on the hex bore Versahubs (217-2592), which are still listed out of stock. Modified AndyMark hexhubs to our Vexpro wheels. The few we did get were great. Fit on the hex shafts though some were too tight. Used a Jewelers file and dressed the flats to get a good sliding fit. Next year we will machine the shafts to .500 d. and key to 1/8 as in the past for better concentricity. Initial shortage of hex bearings created a lot of anxiety as well.
Longer shafts on the ball shifters for wider wheels on WCD would also give more design versatility. We used an additional hex bearing in our frame on the shaft of the single speed tranny to take some of the load off the shaft bearings in the housing. Couldn't do that on the ball shifter due to the shorter shaft.
