the engines themselves are super reliable. We raced ours hard throughout the entire 2010 LOORRS series, and the only thing we did to the motor was change the clutch once, and the oil and filter a few times. Plus, the car went end over end a few times, and always fired right up afterwards. And in race conditions, we are running the motors pretty much wide open for 20 to 30 minutes at a time.
The Weller kit is the most economical way to do it, and super strong, but the main disadvantage is you loose revese, and the gearing is pretty tall. Tall as in the car really doesn't like to go slower than 15 miles per hour. You can always get a bigger rear sproket, but to my knowledge, nobody makes one in steel. Just aluminum, and the aluminum won't get you through a full season of hard use. So you are going to loose any low speed drivability. (reverse can be added but will require some fabing with an electric starter motor etc) The SV1000 engines have more slow speed drivability because they have more power on the bottom end, vs an R1 motor. Plus, they are an easier fit into a stock rhino, as they are narrow, and don't require any mods to the seats frames and such.
If you go with a gearbox set up, they will have more drivability. But you want to run the largest sprockets you can to the box, because the smaller they are, the more heat is generated, and you will have problems keeping the chain cool, and lasting a long time.
Its hard to say if what you get will be like a can or worms, because that really boils down to who did the install. If its done properly, it will be super reliable, and you will have zero issues. But if it was kinda hacked together by someone that didn't really know what they were doing, it could be problems.
Good luck!
