Thanks Jim. I'd never knowingly ridden a bike that had this installed. Had never even eyeballed the parts until earlier this morning. Really wasn't a robust looking gear set. Lots of nearly square edges too. Looks and function aren't always the same thing. But the look wasn't one to give a guy the warm fuzzies.
For what it's worth, here's my thoughts.
My buddy has a nicely built custom bike with a RevTech 110 and their 6 spd trans. It has a 3" belt drive to connect the two.


I've ridden this beast and it very much chits and gets.
The trans shifts very smoothly and I didn't see any issues with neutral or getting into gear. I would think that RevTech would use the same design for theirs as adder kits. I may be wrong, but I've heard this from several local people that have ridden RevTech equipped bikes.
Now as far as the squareness of the gears. Keep in mind that what we have are constant mess gears in our transmissions. All that changes are the "dogs" in between the gears, so the edges should have no affect on shifting.
I've not personally seen other 6 speed gears sets, so have you been able to compare the RevTech gear set with say a HD 6 spd gear set? Putting a 6 spd in a 5 spd case will require some compromises to the gear widths. You cannot compare the RevTech 6 spd to a new HD 6 spd gear set for a 6 spd trans, I'm sure there will be a big difference in gear widths. Just a thought.
I bought a 6 spd Ulitma and was told that it would be good for up to or slightly exceeding 120 rwhp. I have their 113" motor and 2" old school belt drive. I'm sure that the Ultima trans and RevTech transmissions are pretty close to the same in strength. I'm not going to baby this and neither does my buddy with the bike above.
I know it's your choice on buying or not and it could be a safety issue, especially if it locks up on you going down the road, but I've not heard of any failures with the RevTech transmission either locally or in reading forums around the web. We have several local guys with them and they all do their share of banging gears from time to time.
I guess I've not helped much, have I...
If the $350 is all one can afford at the time, it may be a good alternative until another unit can be found.
Good luck on your decision.