I would guess the Lexicon is uncategorized because the plug-in is not included in a recent version of SONAR. I did not install it on my newest machine, IIRC it is a DX plug-in so it must be 64bit to show up in a 64bit host. FWIW, all 32bit VST plug-ins are indicated as 32bit in the plug-in list.
 
REmatrix Solo is a PC module.

+1 for MMultiBandConvolution

Ah ha! I  see I do have 8.5 installed on this laptop so that explains the Lexicon. 
I also have a real Lexicon 200. It is supposed to work as a plug in via USB but they never updated the software and I believe it only runs on XP 32 bit. I sometimes patch it in with analogue but it's a PITA. Too bad because there is certainly better sounding reverbs in the hardware. 
Pro channel is something I have never found useful, everything I try seems like it makes no change to the sound. I must be doing something wrong but I've tried over and over and I guess I just don't get it. So I'll just have to read the instruction documents and stop trying to make it work by pushing all the buttons :} 
 
The other one I'm struggling with is the reverb in AD2. Talk about not user friendly. I've yet to adjust it so it makes any improvements.. more reading I guess...

Cactus Music
I don't see a REmatrix on my list I guess you folks are talking about a none included plugin. 

Check your ProChannel!

...and also check out my "idealized" IR impulses that were part of one of the updates. They were synthesized so they're super-smooth, with a "tail" and overall sound that lacks the irregularities of a real-world impulse. 

Also, check out Reverberate by Liquidsonics - that's a really good IR reverb, and not too expensive.

UPDATE - OK it's £80 now. It used to be cheap, and I got a cheap upgrade to ver 2. It is a good IR reverb though...

Yes, when it looked like PS wouldn't be updated, I looked for 64 bit alternative and bought Reverberate (and of course Cakewalk threw in Rematrix...). 

Liquidsonics supplied some great impulses, you just tell it where your folders are and it finds them (no importing necessary) and it is what they call True Stereo, with some fantastic, spacious convolutions of real spaces. It also has controls for everything, down to the smallest detail.