Subwoofers with room correction built in?


Who has experience, good or bad or whatever, with the built-in room correction/DSP/EQ that newer subwoofers (except REL) come with these days?  I’m excited to try the system built into an ELAC sub 3070 that’s coming my way soon, but I want to be realistic.
Thanks.
redwoodaudio
The Anthem Room Correction on my Martin-Logan Balanced Force 210 sub is nothing short of outstanding.  The difference between no correction and corrected is the difference between bass that goes in and out, depending on the note, and sound that is equal in volume as the bass player goes up and down the neck.  Quite beautiful.

I only have one sub though.  Perhaps it would be less noticeable with a DBA.
@docknow and @doctors11 -- I hadn’t considered a Martin Logan sub -- thanks for the tip. Glad to hear the room correction is seriously helpful.  Interestingly, the balanced force sub has two drivers in opposition like the elac.
From what I've read, you should run something like REW to verify the outcome. You may end up with better or worse results than setting the subs up manually using tools like REW. I wouldn't assume it's going to be better just because is done automatically.
For home theatre, I run Anthem ARC, but don't really care what happens with auto correction. Personally, for music, I don't see the benefit because I'd use REW anyway. 
True room correction is not totally true even in a preamplifiers 
it Averages , Svs has several ANalog Devises 52 bit processors a great app , and you can fir free down load a subwoofer room correction program ,just buy a USB Mike ,  call Svs they can educate you on it to truly flatten your room acoustics 
2 subs are by far better then one also.
Vandersteen Sub 3 11 band EQ same adjustable as Quatro,Kento and 7s

Enjoy the Music 

Tom