I am guessing that you are looking for that satisfying ummmph the movie creators feed to good subs. IF that is the case, go with the 600 or the two 500s.
Unless his seat is in a null location and then he gets nothing. Doh.
OK. That is solved for the most part by the "Subwoofer Crawl" and such for best placement, but just sayin'....
I was a very happy, single-subwoofer person for 9 years. Then I added a second matching sub, and not only can have louder bass, but it has smoother response in the room, and I nearly reduced all overpowering peaks and the "non-existant despite a large powerful sub" nulls.
So watch placement if going with a big beast and you will probably be OK.
I will leave you all with the following information. This is NOT my information, but my gathering of numbers and notes from real industry experts. I used these notes for my final tweaking and such, and for future notes (so that I don't have to find this again.) Note the subwoofer section.
To avoid harmonic peaks and nulls in the room, seats should be placed at one (or more) of the following locations.
.20, .32, .45, .55, .68, .80 of the width of the room
.55, .68, .80 of the length of the room (away from the front solid wall) FRONT SPEAKER IMAGING:
Locate the front left and right speakers and the center of the main seating such that it forms a 45* angle.
Do NOT sacrifice the above seat location calculations.
A 45 degree angle gives good sound imaging.
Toe-in of front left and right speakers helps since most speakers perform better that way with mid & high frequency dispersion.
(I had a graphic here that just showed an ideal angle of 45 degrees when measuring the angle of the width of the front R and L speakers from the main seat.)
Like tow-in of the left and right, aim your center speaker, up or down, so that it points towards ear level in the listening area.
Below screen is better than above screen for center channel imaging.
It usually is closer to ear height.
Height of front speakers should be around 40” from your desired measurement point of the tweeter, midrange, or somewhere in-between.
Do NOT put the center channel more than 2 feet above or below the front left/right speakers if at all possible. SUBWOOFERS:
Standing waves are a big issue with low frequencies.
To eliminate as many standing waves as possible, you need 4 subs.
Place 1 in each corner, or 1 in the middle of each of the four walls.
If you can’t do 4 (10”) subs, do two (12”) subs with one in the middle of each of the front and rear walls, or the middle of each of the side walls. One large 18” sub < four 10” subs