I have the Hsu and it is very good as well as being very good for the money...no complaints at all and great value for the money. Very good with movies - which is what it is meant for....
The Ventriliquist's center speaker is a lot bigger than the fronts/surrounds, so you kind of dont lose that lower mid range like you do in quite a few sat systems.....
The Omnisat do have good reviews - and for US$700 they are near to the exact same price as the 6.1 Hsu with the VTF2-MK2 sub....
I guess you gotta have a listen. Do I think the Hsu is a $1,500 system..not at all and if you can get one for the same price....go for it..
I also have the sub hooked up to my hi fi amp (which is a separate system for me) and whilst I don't use it that much, if i want to really kick the LF...on my more modern music.....it rocks!
Good luck....