I know what that ski is like at +3 to +7. I know a bunch of people who have crept further and further forward. I know no one (out of about a half dozen) people who use the ski regularly behind +4. The only person I know personally who skis with the general crowd you reference skis them at +9.5.
Yeah, there comes a point where you are biasing toward skiing backward as much or more than forward. So there is some reasonable threshold for pushing forward. For example, my kid who just pushed to +9.5 spends a bunch of time skiing switch and buttering and blocking and leaving RR tracks every which way - and is used to the feel of EPs on the mark... But the simple reality IMO is that even when skiing primarily forward, Hell Bents are far more consistent in chop and on harder surfaces when rolled more from the center. And I actually like it better in powder too.
If you know where Mahre and Fujas have them mounted (as in you've seen their skis or talked with them), I'd be genuinely curious to know. I've heard they ski quite forward (exact position not specified). And use the 179s day to day most places. And run relatively softer boots as they don't need to slam through the tips... Reliable contrary info would be intriguing... As for Pollard (who is not a Hell Bent guy, unless you know something the rest of us do not) - check out the single recommended mark on the EP Pros. Those skis are essentially identical in size to the 179 HB and the EP Pro mark will put you at approximately the equivalent of +9.5 on a Hell Bent (we just did the side by side exercise a week or so ago).