JB and Gary,
I remember the first generation of mass produced rockered skis, and I think JB's assessment of them is correct: Floppy in anything but powder, unpredictable in crud and mixed conditions (when coupled with carving technique especially), horrible on hard snow (I had one miserable day a pair of k2 Hellbents a number of years ago...and it was a powder day!).
But last year I used some very impressive designs that handled varied conditions at a level I would have though impossible for similarly shaped skis a few years ago. The s3 being one of the most notable examples. Accepting that we are not talking about skis as cross-over groomer skis, but off-piste dedicated skis with a bias towards soft snow (be it powder, crud, crust or corn), The newest skis--especially in the 98mm waisted category, have thoughtfully taken the new shape designs to impressively versatile levels. And while a ski like the S3, and maybe not even the Bliz Bonafide, will ever pass the PMTS muster as a constantly self-corrective carving ski, it can and does make nice round turns (created by flexing the legs and tipping the feet and ankles) in all kinds of snow. It lowers the threshold for 'terminal velocity' needed to ski soft snow with float, and it does really well in mixed crus/ hard snow. I can't describe the tip as 'floppy.' And yes, no doubt the ability to drift, side slip, spin, and foot steer in tricky snow is an additional benefit I and many others like. There is undoubtedly a trade off in hard snow performance and 'learning to carve reinforcement traits' (which I understand is very important to the PMTS gang) but, I think now those attributes come with a much smaller trade off in hard snow performance than they used to. Small enough, in fact that even strong, edge-oriented experts will often opt for skis like these as their daily drivers on appropriate mountains.
I ski mostly with guys 10-18 years my junior, in their late 20's/ early thirties who absolutely rip...a not tail-gunning rip, they throw these skis over and haul...their turns are certainly shallower, longer (and way faster) than what I'm after, but they own it in bumps, trees, groomers, air, Back country you name it. They all ski on skis like these (ok, I'll admit one guy actually skis on the 161cm Shaman as his full time ski...and he is probably the best skier of the bunch) at terminal velocities that would make a race stock GS ski flop. And yet these skis hold up under these demanding, strong skiers (and yes they are experts, most of the raced in College-two at U Vt).
I know a few years ago these guys wouldn't have clicked into a rockered design, and for all the reasons that JBotti has elucidated, but now-it is all they'll step mostly for the reasons I've mentioned.
You know, when I first got turned onto PMTS (somewhere around 2002) fat skis were verboten, but I see now HH has come around-and probably because Fat skis got better. In a few years maybe we'll see the same passive acceptance for a ski with a bit of an elevated tip.