I have had my VTF-15 in a down firing position for about 2 months already and it smoothed out ALL of the ear pressure i was getting at high levels when watching movies after calibrating with Audyssey. I like the down firing position so much better that i have not moved it for the last two months and it is staying there!
In my 17x24 theater the improvements are...
ALL ear pressure during movies and music is gone
Even MORE feel since all of the pressure waves are hitting the floor!!!
The bass is tighter even in Q 0,7...which is nice.
Hits harder and deeper than before.
I think that the reason i was getting the ear pressure with the regular recomended settings for the VTF-15 is that my theater is all solid wood including ceiling and floor....no leakage...maybe just too much energy being fired at the center of the room. This may not be your cup of tea...but in my room i am a down firing subwoofer guy for sure!!!
Btw..before this i also tinkered with lying the sub side ways and spinning the sub in all directions with the driver facing away etc. Hands down the BEST way was the down firing position...it just hits SO much harder with no ear pressure at all. And oh yea, i also tried it with the driver facing the ceiling...not so good