Vandersteen Sub woofers v Rythmik Subs


I really love the idea of the Vandersteen Subs where they are connected with the mains via extra speaker cable off right and left channels off the main amplifier, which is supposed to provide better bass transition from the mains while keeping the signature from the main amplifier. My question is with Vandersteen coming out with the SUB THREE and the price going significantly higher, I was wondering if there are other subs for less that you could integrate in the same way. (Most subs seem to rely on the line level input which is just a sub-woofer RCA going from the pre-amp to the amp on the sub). Can this same Vandersteen set-up be achieved with other subs?
I picked Rythmik since they are known (in the home theater community anyway) for being one of the best bang for the buck subs and the most "musical" of the bunch. (between Hsu, SVS, PSA).
And could I possibly achieve even greater sub-woofer nirvana since I could get an 18" for around $1500? Vandies only have 3 eight inchers.

I am a Vandersteen fanboy and I would like to support RV whenever I can, but don’t know much about my other sub-woofer options so looking for some feedback. Doesn’t even have to be related to Rythmik necessarily. If you know of other subs that can integrate the same way I want to know about it!

Thanks
bstatmeister
Vandersteen sub will annihilate anything from Rythmik. It's musical and tuneful and integrates well with many speakers and rooms. It's as good as the best out there. It's not even fair to compare the two.
@invictus005 - I am not disputing what you say, but I am curious as to how you arrived at your conclusion.  I love my 2Wqs, but the Rythmik clearly has some fans here.  Have you compared the two?
I happen to own them both and neither one obliterates the other.  They are different paths to the same goal. 
I happen to own them both and neither one obliterates the other. They are different paths to the same goal.
How do you implement the Rythmik sub? Do you use the line level in from the preamp/receiver subwoofer output?