I take the issue of advertising as "patent pending" seriously. Not to go into why anyone would have kept it in that state for 17 years, people have strange habits, but it does seem suspicious to say the least. Lawyer costs, or not.
The issue at hand is that we are talking about an item which is very unusual in its execution and proposed action so it may or may not work as advertised (according to two camps here). Decision to invest quite some amount of money in it is largely on credibility of the manufacturer and her/his claims. If said manufacturer has been marketing by claiming something untrue regarding patent ("pending") for years, how likely is it that the rest of the claims are believable? Not to mention that, if those links above are correct, it is even a punishable offense.
Way before writing this post, in fact before ever mentioning this patent issue in my posts, I tried to locate the patent for Hallograph with no success.
In short, scrutiny may be in order.
Having said that, it seems that claiming impossible-to-verify patents is not unheard of in audiophilia. There was at least one product by PPT that was falsely advertised as being patented. Even one of the Tekton Design patents has expired (fee related), but it may be deliberate and it may take some time to connect claims with actual patents that are active.
To be clear, I am not claiming that any of the products do not work as advertised. I simply state that claims about patents are dubious. We all have our pet peeves and this happens to be mine.