The 400 is a fantastic sub.
There is a lot of posts on the Subwoofers and Tactile Transducers section on comparing the 200 v 400 v mono v mono+
As I was so impressed with the 200 I thought the next logical step would be the 400. great sounding sub and size. but the mono just goes lower.
im not as smart and technical as the guys on here, but its great to get so many opinions. i was 50/50 on the 400 v mono. At the end that deeper bass sold it to me and i just got the mono+. I had the space so this helped.
the 400 is perfect if you want to save some space.
Do a few searches on the cub section and you will see it comes up week-in week-out.
All I can say is that AVF has cost me soooo much..... but its made my life of home cinema the best.
when anyone comes over to my place and they see the 106" screen drop and then the rumble of subs etc...
A) they have seen nothing like this and are sooooo impressed, especially the ladies
B) they are not only wowed! but the girls are jealous why they married a plank, they always say to my wife that she's so lucky and go on why their other half couldn't ever do anything like this etc.. (makes my wife happy)
sorry don't where I was going with that...too much coffee already.
Go with your gut feeling.
do your check list, size, price and performance. you cant go wrong with the 400, the mono is just a bit extra.
also I always like to say "look at the size of my sub" yes my wife calls me sad!