So, I'm wanting to take Overloud up on their generous crossgrade offer - already have my codes.  I haven't used a lot of the IR technology and know I'm showing my ignorance but I asked Overloud about these two thinking since they are both convolvers, they both use IRs and which to buy? :)  Here is their kind and concise reply - hope it helps others:
 
"As for your question, I must point out that, unlike REmatrix, BREVERB 2 is not a convolver based on IRs: its processing is entirely based on algorithms.

 
Just to clarify, this means that its response to the input signal is entirely "calculated" according to the chosen algorithm and the values set for its parameters, and not upon any pre-recorded sampling of some particular room/space.
 
That is a substantial difference between the two products and, as you may have guessed by now, it means that it would not be possible for the presets of either of the two to be compatible with the other." 
 
Best regards,
    Federico
OVERLOUD Support Team 
__________________________________________
 
So, I'm thinking of going with REmatrix since I do have the Waves IR-L Convolution Reverb as well as other fine Reverb VSTs.  The REmatrix demo looks to do some quite interesting things.  But I know many of you really like Breverb. Thoughts?

For my money... ReMatrix is the one to go with.

I forget what the upgrade pricing was offhand, so only have the SONAR-based versions that were unlocked but prefer REmatrix as well of the two.

Thanks!  I think I'll go for TapeDesk as well.  Here are the prices offered:
 

Upgrade to TH3 Full €119 / $119 (reg. price €299 / $299)
Upgrade to BREVERB 2 Full €99 / $99 (reg. price €199 / $219)
Upgrade to REmatrix Full €129 / $129 (reg. price €299 / $339)
Upgrade to Gem TAPEDESK €99 / $99 (reg. price €199 / $199)
(possible replacement for Cakewalk Console Emulator and Tape Emulator)

Is it really a fair comparison when one is a convolution reverb and the other is algorithmic? Two completely different methods, although after watching some vids the control factors you get with ReMatrix is pretty amazing.
 

fwrend
 
Upgrade to Gem TAPEDESK €99 / $99 (reg. price €199 / $199)
(possible replacement for Cakewalk Console Emulator and Tape Emulator)

Far superior to what is included in SONAR, the CE in TAPEDESK is based on the PC CE (Overloud were responsible for the  2 PC modules)but updated and enhanced, the TAPE part of TAPDESKis all new.

This sold me on Tapedesk:
 
https://www.youtube.com/watch?v=jHgUyS9aYBg
 
 

emwhy
Is it really a fair comparison when one is a convolution reverb and the other is algorithmic?

 
No, it isn't.  The "vs." in my heading pertained to my purchase decision only.  Frederico set me straight on the differences.  :)
 

emwhy
Two completely different methods, although after watching some vids the control factors you get with ReMatrix is pretty amazing.

 
Agreed!

+1 for rematrix... It is truly powerful.

+1 for REmatrix. I have only just started using it, but I love the natural sounds on vocals. It was so easy to tweak it the way I wanted it. I tried to get something of a similar quality from Breverb but failed.