I went with a Mud Skipper kit since it was about $200 cheaper with shipping. It's a great little longtail. The Swamp Runner would be a better choice, for a few good reasons, if you have the money. The only issue is making sharp turns in a river or channel since the shaft is almost as long as the boat. I haven't taken it through deep mud, but it will go through very shallow water as long as the bottom of the boat doesn't drag along the bottom.
The Predator engines are great. I have had one for a while now with a stage 1 kit installed (air filter, exhaust, timing key, jetted carb). I think the majority of the problems with these motors occur when people take parts of them out and upgrade the crap out of them. I posted a video not too long ago of a guy that did everything to his and the crank case split in half. He explains that it happened because the motor wasn't designed for running constant RPM's over what the factory said it should. If you want higher RPM's, go buy the 14hp. But that's just my opinion. The motor will last as long as you take care of it. Break it in with regular oil before installing it on something, regular oil changes, add sta-bil each time you put gas in it, and run the motor at least once a month.
A BAD DAY AT THE MARSH BEATS A GOOD DAY AT WORK.