Josh, first of all thanks for joining the forum & welcome on board! I'm glad you don't take comments at face value and question. As always though your ears should be the ultimate litmus test.
Re: my comparison to the IRS-V's, I should point out I was careful to say "by all reports" as I have not personally heard the GTA3r/SI speakers yet. I based that on commentary from Peter Breuninger and Kemper Halt who have reviewed the speakers for AV Showrooms. Watch
this video. The review starts at 7:19. In it PB compares the GTA3r/SI600 speakers to the IRS-V's. Kemper also describes the enormous bass impact of the Sound Insight servo subs.
I also privately discussed the comparison bewteen the GTA3r/SI600 speakers and IRS-V's with PB, and he had this to say -
"(Me to Peter Breuninger) Peter, are the GT Audio speakers with bass towers really in the league of the IRS-V's? The bass towers remind me of the Linkwitz open baffle bass topology..
(Peter Breuninger) Yes, absolutely. I have lots of ear time on IRS Vs... at HPs, Bill Legalls, and Kevin Olsen's house. The GTs have a better midrange and bigger soundstage."
Re: your question of whether the SI600 open baffle servo subs can match the maximum SPL's of the IRS-V's woofer columns, I got this response from Greg Takesh at GT Audio Works which i'm sure he'll be happy to confirm -
"The GTA3R and sub combo are visceral on a level achieved by few speakers at any price.
Honestly...you have to be careful, the subs will do 15 hz at 120 db..you can hurt your ears !!
Feels like when you descend in a plane and you feel the pressure on your ears, and your ass vibrates in the chair !!
Its intense !!"
The GTA3r/SI600 system, being a dipole-radiating line-source speaker also enjoy the following benefits -
"The advantage of a line-source loudspeaker is that sound pressure level falls off at -3dB for every doubling of distance away from the loudspeaker instead of -6dB as with a point source loudspeaker. Hence, a point-source and a line-source loudspeaker with the same sensitivity at 1m will have a 6dB difference at 4m. The line-source loudspeaker will have double the sound pressure level at the listening position." - Gary Koh, Genesis Advanced Technologies.
Hope that helps.