I use Har-bal sometimes when working on restoration projects - it can be useful to get you to a result that would have otherwise taken ages. Also it's good if you are trying to give a bunch of tracks a 'feel'.
I believe that Andrew Rose uses it extensively, but he gets up to tricks that he might be less than willing to share (and I don't blame him) - because they give him a commercial edge...
Wasn't looking for enumeration of tricks, or even pointers. Even before they were introduced in AA (beyond the basic frequency display) I had some frequency space editing tools with which I was fairly comfortable. Between 1.5 and 3 the frequency space editing seemed to become significantly more robust (though that could be because I didn't explore that aspect of previous versions of AA). While I wish I understood a little better the how things were executed I'm more or less OK with practical results I've achieved, particularly when combining various frequency space editing with approaches and tools I've already refined through years of use. Frequency space editing in AA wasn't like a jackhammer plunked into the middle of a tool kit filled with whittling tools and x-acto knives used to construct model sailing ships. So the principal curiosity was not 'how' har-bal improved on the basic AA editing (as opposed to trying to tune speakers to a room) but merely whether it did for general editing.
While I was inquiring directly whether Andrew used Har-bal that wasn't because I think there is all that much overlap in type of audio work we do or even in how we might approach it. For me I'd be curious whether Har-bal might help me improve the sophistication and speed the process of that sophistication in turning raw concert/club recordings into salable artifacts. Even when there is time for a reasonable sound check that is seldom coupled with enough time or hands to optimally position mics for tracking. Even with DI's & drum triggers there is always significant bleed in important voices. Neither are we ever mixing this stuff in optimal surroundings. And answer to that can only be optained by trying it . . . among tools of retracking, resynthesizing, regenerating with enough time I can already convert nearly any 'live' track into something resembling studio sterility. Whether Har-bal would work for me is a question as intimately entwined with 'how' I do things as it is with Har-bal's inherent tool set.
The price tag on Har-bal was/is not particularly off putting but at some point attempting to learn yet another bit of software will be one 'somebody else's logic' too many and my head will explode. And while Har-bal's claims are perhaps no more grandiose then, say, Melodyne's (which I also use) for some reason Har-bal's marketing always just sent me spinning in the opposite direction. (& will admit a degree of snobbish prejudice of which I am not proud; if C. Anderton recommended a Weiss dynamic EQ or Siemens V72 my knee jerk reaction would be that they were pieces of junk)
From what I have heard of Andrew's audio reclaimations my gut reaction is that less of it depends on some special magic sauce (i.e. Har-bal) then accumulated experience from obsessive attention to minute detail. So, as testimonials go, if someone with Andrew's skill set finds the app to be useful it might be worth the $100 to check it out. (For the record it's not that I have less respect for Steve's capability (and/or obsesivness) but I have had a lot more exposure to independent 'before' versions of Pristine Audio's offerings.)