Vance, I’m using the PF-120/125 plastic frames (mediums). When I saw you mention Mann Lake 4.9 cell size, I assumed you were talking about them. I’m happy enough with the PF mediums. They’re rigid enough for my hobbyist needs any my bees work them. I would be more worried about the deep versions though since they would seem more apt to warp and distort (due to the larger surface area). I don’t have any experience with the deeps. Maybe somebody else will chime in.
The whole reason I went to plastic was to avoid all the time it takes to put together wood frames. This is why I really hated trying to paint the darn things, it just took too long. Like Michael Bush says, the PF frames/foundation come with a very light coating of wax, which seems to be enough.
I really liked the videos Allen attached. Although they were just dipping foundation itself, I suppose that process would also work for a PF frame/foundation combo if you really wanted to add more wax.