Actually,
not reviewing the usual suspects is by design.
Ask a question on the forum about virtually any SVS, HSU, Rythmik, etc. sub and you'll get 50 owners responding. You can find a multitude of reviews on just about all of them as well. I didn't feel there was anything I could contribute to that situation -- they were all well known commodities -- so when I set out on this journey I asked myself "where can I provide value"? The answer? Unknown, or little known, companies.
When I started down this path it was as an independent nobody (which really hasn't changed, to be quite honest). What established company wants to send a subwoofer to get reviewed by someone like that? None of them, as it turns out, so I bought the first few units myself, did the reviews and then sold them. Cost me a couple of bucks but there was a method to my madness; now I had something "published" that I could point to when asking a company for a review unit. That got my foot in the door, so to speak, and gave me some momentum. At least enough for the obscure companies, who couldn't get anyone to even consider doing a review of their subwoofers. Then a funny thing happened because of that momentum; it seems I unwittingly tapped into a need that the industry wasn't fulfilling, and things started to pick up at a breakneck pace (which goes a long way towards explaining how I ended up with so many subwoofers waiting to be reviewed

).
There's a whole lot more to my story, but cutting to the chase... now I actually get review units from some of the mainstream players in the industry. Companies like Atlantic Technology and PSA are more then happy to let me do a review for them. Did you know I was the first person to get a PSA XS15 to evaluate? I suspect this will come across as egomaniacal, but I'm pretty d@mn proud of that. A year ago was when I published my first review, now I have units lined up and companies asking me to do reviews. And you should see some of the others I'm working on! There are a few pretty darn impressive achievements in amongst them, assuming I can pull it off of course.
BTW... Axiom is among the companies that told me "thanks, but no thanks". Others who told me the same thing, or simply never responded to my requests, include Fluance, Home Theater Direct, Sonance, Phil Jones Pure Sound and James Loudspeaker (among others).
That's not a bad idea, but the trouble is I simply haven't found the "holy grail" of subwoofers yet. At least not by my interpretation.
For me, clarity, dynamics and precision are absolutely paramount. Meaning more then likely it will have to be acoustic suspension. Relatively small is mandatory as well -- say, 18" squared. It must have exquisite build quality, and be able to hit 20Hz solidly. SPL's are not a factor for me, because I don't listen very loud. It needs to have good output capability, but 110dB @ 20Hz is just not vital for me.
An example would be something like the James Loudspeaker
EMB1200, which seems ideal for me. I almost secured one for review, but alas it fell through. Initially the person I was dealing with showed great enthusiasm for me doing a review, but that waned as time went on. Soon he almost completely stopped repling to my emails, and when he did it was only terse responses, so I backed off.
However, not having a reference sub yet doesn't necessarily mean I don't have a reference point. All of my reviews -- every single one -- has been done with the price of the unit in mind. What I would consider excellent response from a $400 sub would simply be mediocre if I got the same from an $800 unit. Price is somewhat relative of course, but at this point I think I have a fairly good understanding of what someone's subwoofer dollar should buy, so all of my reviews are weighted accordingly. Not an exact science, but at least it's somewhat of a benchmark for me to go by.
Hopefully I will have a reference subwoofer to use as a comparison, but sadly I have yet to find it. Someday perhaps...