[RC-Monster Mike]

The picture shows the "truggy" ratio, which has a high helical pitch on the ring and pinion gears. The "buggy" diffs also have a slight helical pitch(look close, they do have a slight curve), but it is not nearly as noticeable. You won't likely have any difference in overall reliability - the major difference is in the final drive ratio.
These are tough to keep in stock at the moment - getting and modifying the pinions is proving to be the biggest challenge. I should have the V2 ready in another week, which will accept standard(un modified) diff pinions with custom bearings and will include an 8mm drive cup. The V2 will also accept most 1/8 diffs(kyosho, ofna, Hot Bodies, etc.), so the cases can be sold seperately without the pinions.
These aren't a cheap product to manufacture, either. The shafts are custom made, the cases are of course custom made(and required loads of work to complete), the bearings are custom made(last batch and future batches receive the flanged bearings with a rubber seal on the outside for optimum protection and metal shield on the inside for lowest resistance). Lots of time and work is required to put these together - the good news is that these will likely be the last diff upgrade you need for the Revos(1/8 diff set - $250...finishing the race without blowing your diffs - priceless)!