Towers with built in subs vs separate subs

fuzztone is exactly right. 

Ported or sealed no amount of room optimization, correction or equalization will ameliorate the sound stage optimized null location of your speakers and allow the ability of -3dB subwoofers their full potential for room and system integration and performance. 

Your REL isn't nearly as restricted by room positioning often placed next to speakers. Since their lowest frequencies are down -6dB sub-bass speakers simply do not excite a rooms modes like subwoofers, at the expense of extra low frequency detail and heft. 

Save your money and just use the REL.

In the mean time try and organize an in home comparison audition of dealer positioned Vandersteen Trio's. With your family present you'll easily hear Paradigm's coherence paradigm. For me this became a far greater priority after living with three of the Canadian's top models.      

A built-in subwoofer will perform better for music. The texture and pace of bass notes will better match with the main speakers.

I don’t think this can be said so universally.  Often times in a given room the flexibility to place the subs where the bass sounds best in the context of a given room is extremely important and consequential in determining the final performance results.  If you do the proven “sub crawl” method to determine where subs/low bass work best in a room I highly doubt those locations will end up being within the confines of the front L/R speakers.  In short, you’re largely fighting room physics by requiring the subs/low bass to reside within the main speakers.

@ditusa ,  multiples simply aren't an option unless i stack them. I have 2 options as to placement...next to the R or next to the L.  My first choice would be to get a bad ass rel s series, but.....if placement is that important ,Im limited.  So why spend the $$

glennewdick 

Thats quite an endorsement saying the paradigm are better than the focal. 

Mr Soix,   i guess my question would be to you and others that think separate subs are better,  and i agree, they probably are, but can the room correction in an imperfect room with limited options as to placement get close to the results of doing a sub crawl with multiple placement options?