Well, the full THT has crazy output. I'm shaking the floor at about 1/4 output. I think your 12" shiva driver has 1/2 the output of the DVC 15 that is in the THT (if I remember correctly).
...so get yours built, then find out at what level the floor starts shaking.
To tell you the truth, the output is too much except for when someone comes over and you want to "show off". You can't listen to more than a couple of songs at even half volume. It's just too damn loud! Oh no, I'm being banned from AVS!!!
For normal movies, loud is ok, but I can't imagine having WOtW at full volume for the full movie. I think I would have PTSD afterward.
I have to get the level of the highs and lows better matched at higher volumes. The highs are overpowering at high volume. I have the Audyssey dynamic EQ turned on and there are a few different modes....
In summary, tou really should get yours together if you have the time. You have all the parts, from what I remember, so you won't be spending money.