Stereo Subwoofer Pairing

I'm thinking about using either a used Rel T7 and a new Rel T7i or a used Rel T5i and a new Rel T5i with Magnepan .7's.  I have the T7 and the T5i in different systems right now.

Followup question on Rel's specifically.  Can I use a new i edition of the T series with the old T series?  Or are the model changes major enough that they won't sound similar.

That would be a question best answered by REL.
B

I asked rel.  I'll post their response here.

rjb1101,

     If you set it up just so, you could become the first human in the history of our species to be able to hear deep bass in stereo.  
     Where'd you get the idea that stereo subs would be a good idea? Or even discernable.  
     Sorry, stereo deep bass is a myth so it's probably best to keep your expectations very low to avoid the inevitable disappointment.
It's not too late to save some time and money and abandon this nonsense.

    Tim