My perspective is a bit different than davluri's. And involves no posturing on the part of anyone.
On some of the newer ski designs, the "suggested" mark is sometimes a significant compromise. To my mind, the benchmark example of this is the Hell Bent (let's keep to the old one for now). It has a huge range. zero to +7.5. And really jibby types often went to true center at +9. K2 had a "recommended" mark at something like +2 IIRC. In reality, that mark seems to have been a weird compromise - targeted at more classic "driving" style skiers, racers, etc. And intended to let heli/cat clients hop on and & use the ski in powder. For those people in particular, it allowed their "get over the tips" style to work well enough to get by. But in reality, the ski worked best when skied "from the center". And the tendency of "classic" skiers to drive their tips limited the utility and feel of of the ski.
This is, IMO, part of why there is such a wide span of opinions on this class of ski. So.... it pays to understand each ski well & how the designers and top level users feel it should be mounted & skied. In the case of the HB, virtually everyone who understands the ski & has taken the trouble to learn it is forward of +5. Most forward of +6.
This pays dividends under all conditions. In powder, it has the counter-intutive effect of reducing going over the bars because you are not trying to drive your tips down to engage them (relatively futile on a fully rockered ski anyway). On hardpack, you can engage the ski more readily underfoot. In all conditions, it offers a tiny bit more "tail" - which there will not be a ton of anyway. Even with skis like the S7, the short camber zone reduces the force needed to drive the contact point & decamber the shorter camber area - so you can probably cut down on the getting out over the tips thing (although I admit that I am speculating a bit as I have not skied the S7).
Then, within this issue is the spectrum of use. In some ranges of design, even with in the general smaller "good" range, jibby types will err toward the center of the ski. More directional skiers will likely not err quite as far forward. Athough with some skis that can bring into question why someone really picked that ski (eg mounting a HB behind +6 or so -- I mean just get a Pontoon & be done with it... but mount that +1 ).
So, in short, this is an interesting issue. And the sensible mounting answer for optimal versatility and function on any given ski presently seems to vary by manufacturer, line and specific ski. Tempered by skiing style. Over time, I suspect this will settle down to narrower ranges. But for now, there is legit discussion & debate. And questions. Some answers can be found on certain boards (some not this one) and from shops that know & understand these skis well (eg evo.com, untracked.com, etc. ). And FWIW, my gut sense is that some reps who are well connected or are progressive skiers using those skis regularly themselves know the scoop as well.
Edited by spindrift - 9/7/10 at 8:03pm