If a gear drive was a power robbing way to handle your timing, you wouldn't see F1 using them. I don't think their performance is the reason why you don't see them being run on more engines. The reason is probably cost and complexity. It can be somewhat difficult to make a gear drive that gives you a lot of options on timing. A belt drive gives you a lot of flexibility on timing adjustments while offering a predictable amount of stretch and are cheap. Chains, especially the longer ones, suffer from 2nd order harmonic waves (SOHC) that require dynamic tensioners. While I don't personally have experience with the gear drive system for the FE, I'm willing to bet that it is reliable. In terms of reliability, from best to worst, it goes gears, chains and then belts. Slippage from none / almost none to a little goes gears, chains and then belts. Cost from little to a lot goes belts, chains and then gears. Coef of Friction, from smallest to largest, goes belts, chains and then gears. Someone is more than welcome to revise this list but this is how I understand all 3. You pick what you feel is in your best interests.
