I'd recommend the 133. That's what I have (I almost went with the 121, but then decided to spend the extra after reading about them). As someone else said, I'd recommend them just for the blade they come with (though the 121s may have it now too; on another thread I'd noted that they seem to have a different brand of blade than when I bought mine). That blade is closer to a freestyle blade, which you'll want...pretty quick. And you might as well get used to a rocker and bigger toepick now, IMO. There's definitely a difference, and it's not all the fun to have to switch over (as I found out the hard way with a fantastic belly smacker onto the ice when I caught one of my new, "big" toe picks). I know they cost more, BUT you're not going to grow out of them as an adult so it's worth spending the money, and probably is cheaper in the long run than buying something less expensive now and having to upgrade in a few months anyway.
My 133s required pretty much no break-in period that I noticed. They never hurt or rubbed. They are (IMO) just not high-enough level (read: stiff) to require a lot of breaking in. I've been wearing them for over a year (though lately I've only been skating about one hour a week) and they still work for me, and yes, I do jump and spin (well, attempt to spin) in them. I'm on the lighter side for an adult, though, so YMMV. But when I bought them, my fitter did say she estimate they'd take me through the single jumps (in a tone that suggested the 121s would not have been suitable for jumping).
If the Jackson Mystique comes with the blade I think it does, then Katz is right. Don't do it. I think those would be the skates a couple of my former classmates got, who were told in short order by our coach that they needed different, better blades ASAP. So I figure I wouldn't bother if I were you. Those blades resemble the crappy recreational blades more than figure blades.