Me: 6', 165 lbs, middle aged advanced, technical/finesse, spend most of my hours this season running gates in NE.
Ski: Last season's 168 cm RX12, 70 mm, about a 14.5 m longer radius (rear), I'd guess a 12.5 in front. Runs the exceptional KTi Marker plate, which as Phil noted, is more unobtrusive and linear than any serious plate I've tried. So at my size, a hybrid SL/GS, while I assume the 176 would be more GS-ish.
Several reviews have been written about these, and I agree with the premises - super grippy, super refined race carver - so I'll concentrate on the surprises for me, mainly in terrain or conditions that you wouldn't expect this ski to handle.
1) First, while these are only a notch below SL planted on ice and hard pack - and have as much or more metal, 1.3 mm of Titanal sheets - they make a variety of styles in bumps silly easy, ranging from drifting or rolling over the shoulder to little pre-jumps or bounces off the tops to zippering the troughs. I attribute this to their light tips and uber smooth plate; think "turn" and they do, without the sudden grab in initiation or finish some carvers display. Just stay off the tails and everyone's happy.
2) Second, when I was caught on them in 12" of fresh snow, they were pretty decent. Obviously not floating on the surface, but not submarines, either. The light tips tend to run horizontal, give plenty of feedback without a hint of deviation. They required some extra attention to ski location (closer) and weighting (these do not like backseat in any circumstances, but especially in chop or powder). But that done, they navigated the pow, and soon enough, heavy chop, without drama. Or excessive unweighting. No, not advocating using carvers for freshies, but interesting how much better they were in fresh snow than comparable good carvers. I'd include various Volkls, the Head SS, Stockli CX and Blizzard G-Power in that group. As the chop turned to piles of stiffening crud, the differences became smaller or vanished; I'd take the Stockli in serious muck and the G-Power on frozen ruts.
3) Third, even at 168, the RX12's have a high, and very undramatic, linear feel to their speed envelope. Usually a "hybrid" is more SL than GS. Not here; these may be tractable at with-the-family-speeds, but they have a happy place north of 30 mph, and remain solid at 45 mph, which is as fast as I like to go on civilian slopes. The 176 would make a strong beer league racer, I'd predict.
The comparison here would be with the G-Power at 167, which has a detuned Marker WC plate. That ski has equal or slightly better grip, is not as secure at speed, has a more on/off edge feel, lacks the linear flex pattern (stiffer to near numbness in the middle 2/3, springy at the tip and tail), and surprisingly, it's more reactive in heavy crud. But on bouncy ice, a wash, two different design approaches, handling outcomes. The G-Power at 174 is a better direct comparison, actually, not as quick edge to edge or precise, more of a GS-ish feel, but equally proficient on ice, better in stiff or heavy snow, and a slightly higher speed limit. That's a really fine all around carving ski, FWIW, my previous fav.
4) Fourth, they are less forgiving than I expected. A quote on Real Skiers says, "They made me a better skier." That's the takeaway for me; the RX12's expect you to know what you're doing, in terms of edge angles, COM, and basic mechanics. They'll tolerate some error, but not a bunch, before they remind you something isn't quite right. In this sense, a very different ski than the MX70's, which are same design and shape, 1.0 mm of metal, but neither very demanding nor very planted on hardpack or ice. Or the G-Powers, which are weirdly forgiving of mechanics for such a high performance hardpack ski.
If you treat the RX12's well, they'll dazzle. So a good ski to advance on if you spend a lot of time on groomers and you're committed. Or committable, given the price...