There is no MOSFET version of the MiniMax, as far as I know. That build was designed to fit in the custom case that you can see at the project website. Being small, the case doesn't allow for adequate heatsinking required for MOSFETS, ergo it's restricted to BJT output transistors.
I'd think the MiniMax would be a great build for a newb who wanted to jump right in, so to speak. The casework is basically all done, and there's nothing particularly difficult about the build itself, other than the larger number of parts compared to something like a CMOY or Mini3. Hey, I've seen people successfully compete a B22 as their first build, although I would never ever recommend it. But if a B22 can be completed by a first timer, then the MiniMax shouldn't be a problem, and you've at least had some experience with soldering iron, so that might be what I'd go for.