I've played with maybe ten different mini skirmishes (635s for short) and they all had excellent lockup. I've seen stouter framelocks, but I rather doubt it makes any significant differences. Point being, I imagine it's far more than tough enough for anything I'd need. Clearly, the Manix is beefier, and its also got perhaps the finest ergonomics I've ever used, but the real magic of the mini Skirmish is how small it gets closed. It's only very slightly larger than a minigrip closed. Then that massive blade pops out and you wonder where it all goes when it's folded...
For me, it's all about the mini skirmish, even though I turned one down today. It definitely remains high on my list for next semester though.
Oh, and I'll add that the spyderhole on the 635 sucks for flicking. I have no problem with slow opening it, but my thumb just shoots right out of it if I try to flick. Looks pretty though.