REL strata III vs Spendor Sub 3, which to use with S3/5?

To answer one more point made by some comments, the Strata III has a crossover of 12 dB per octave, whereas the Sub3 has an 18 dB per octave slope. That makes it important to set the REL crossover at a lower number.
thanks for your comments and help

I am looking at the Storm III or the Stadium III. I would like to get 2 of them and hook them up in stereo right beside my 803N's. Are two Stadium's too much of a good thing? or even necessary?

I have two Stentors. I put off buying the second one for a long time because it seemed a ton of extra money for just more bass. Finnally I bought a second one and I was completely blown away.

It was more like replacing speaker cables then just adding a sub. Better imaging, better detail, better stereo seperation. Stereo subs helped in ways I never even imagined. The most suprising part is how much it cleaned the sound up.

Then theres the bass. WOW! Punch and clarity like I have never heard. Not only is this the best music set up I have heard but also the best home theater set up.

I would consider though buying one better model then two lower models. You can always add another one later!

From the specs, I don't think the Spendor goes as deep as the REL. I love Spendor speakers generally but I think the class act in sub's is REL.