it's one of those things, damned if you do and damned if you don't.
The main advantage is that you can run real big cams with them as they reverse the direction of rotation of the rear cam eliminating lobe to lobe interference.
If you use the stock cam plate, some are quiet and some are real noisy. It would be a good idea to use a Delkron cam plate if you use the gears.
We use the chains in most engines and have had no problems with them, but we modify them some.