I'm not going to fuel what's coming across as essentially a religious debate (being happy to fly routinely with a Rotax 912 and the more traditional engines). However, Aussie Bob's assertion re unintended starts needs correction. With the supplied Rotax ignition system, you cannot in fact hand start the engine: it needs to swing at a few hundred rpm before the electronic module generates any spark at all. As a matter of fact, I've tended to regard this as a disadvantage.
I'm also quite happy to use a mixture control but I'd be surprised if I could improve much on my typical 15lph in the Rotax.