Thank you Peter, that makes sense. However, even with that explanation, I still think the VTR-3 HO would be a better choice for me out of the two.
Thank you to everyone else as well, your thoughts and opinons have been appreciated. Out of self preservation, I had to end this and make a decision, and its only right I explain the logic behind it. I have to say however before I start, that I firmly believe all the SVS, HSU and Axiom, are all superior, high quality units with very good performance standards.
I did not go with the SVS based on two reasons: 1) I wanted to honor the agreement I made and not exceed my price limit (however, if it were not for the truly unexpected sales tax issue - I would probably have my SVS by now) and 2) because of the size of the unit (which would have bothered me far less with a nice wood finish, but that adds another $200 to the price). I have no problem with the size of the unit, if it is actually necessary for my HT room. The problem is, there are so many different opinions and acoustial varitions, the only way for me to find out if a unit that size is necessary, is try a smaller one first.
Between the HSU VTR-3 HO and Axion EP500, I decided to go with the HSU unit (at least initially that is). I felt the HSU was the best value, as it would do what I need and wanted it to do and do it exceptionally well (this does not mean that either the SVS or the Axiom would not do the same). With the turbo (which I still think is just tacky looking), I'm positive that it would be fine for a room of my size. And for the most part, I could probably just use the turbo for movies or as a gentle way to wake my wife in the morning!
Unfortunately, HSU is out of stock of the HO until the end of this month. As you know, I have my new receiver (sitting in its box), Monday I will have my Def Techs (sitting in their boxes), and all I needed was my sub to take everything out of the boxes! (I want to do it all at one time because with all the calibrations and tests, it just seems to make more sense that way - plus I have limited time to spend doing it, so doing it once is better for me). Normally, I would simply a month - no big deal, I'm an adult. But, due to all the new components, it would be torture to try and wait that long (I guess I'm not that much of an adult!). So I could not wait for HSU.
As such, I called Axiom and ordered the EP500. The EP500 is the smallest and nicest looking of the bunch (Boston Cherry - no extra charge). As I said above, I think all three are exceptional subs. To be honest though, the EP500 is also the one that I am most worred about not being able to be effective in the size room I have. The person at Axiom says it will be fine (but that's what I expected him to say). I'm not saying that he was not telling the truth, but I do get the odd feeling that the people at HSU and SVS tell you what they think rather than simply trying to sell you a unit.
In any event, my logic behind this purchase is that if in fact the EP500 can handle my room, with the bass that I want, great, I'll be happy. If not, I have 30 days to return it, no questions asked. The only cost to me is $62 return shipping (well worth the home trial). I'm halfway expecting that I will end up returning it and ordering the HSU, but am trying to stay optimistic. (Although I did confirm that if I change my mind over the weekend, I can call can cancel my order no problem monday morning! lol).
Oddly enough, my only concern now is that because almost anything will be far better than my current Accoustimas, that I may think the EP500 is working great, but not realize how much better it would be with the HSU or SVS!
Anyway, thank you all! If I don't change my mind by Monday, I'll be sure to report back about how I think it works in my large room!