Subwoofer line array for 2 channel

I use the woofer towers from an Infinity RS-1B. I personally think this is close to ideal. 

 There is no problem with a stack or a tower of subs but, with only 2, they cannot be spatially distributed to deal with room modes.

Use these the top one won't fall off. 

http://www.rythmikaudio.com/FV25HP.html

I guess the question im trying to solve is:
Is a column or stack of modern day class D amplified subwoofers more effective than some of the older huge woofer columns found in mega systems that use older outboard amplification...l can tell you as far as portability there's no contest....

Well it sure gives you a lot more flexibility.  Than the older columns,

Each box has it's own amp... Can get pretty picky if you want.

It's good, but a DBA will measure a lot better. My issue is 60-300hz
That is the bulk of what most folks call BASS... That's what pounds your chest and knocks the breath out of you. NOT through the bottom FEELINGS. That is sub stuff... More HT than music reproduction...

MB columns (DSP) and a servo SUB system, are the best for me so far.  I'm at the primer stage, gettin' close. Remember too, some of those older columns were servo controlled, The RS1bs you spoke of were not., BUT I've seen RS1B modified with a servo system and converted to LS/hybrids from point source. I use them RS2b, wonderful little hybrid/ LS/PS... Ribbon unit...

Columns rule, the trick is understanding how they work... and what to use them for... I like the fact that they take a LOT less floor space.

Regards...