Just an update. Sorry I got a late start today (feeling like crud... it happens).
This was indeed a result of me not having installed the necessary SONAR versions required to run Drum Replacer. I thought I had last time I accessed my store account but after looking through my files I had actually downloaded ALL versions of SPlat and ALL the extras associated with those versions and installed ALL the extras but had not actually installed any of the SONAR updates themselves (which is why I was getting the message).
Essentially I was still on Dorchester when I thought I was on Gloucester. Total user error/Beepso brainfart. Perhaps one of the downfalls of being an "offline" installer without CCC but I seriously did not notice until this DR thing so no bigs.
Due to the fact I'm feeling crappy and derpy today I did not go through the process of downloading and installing Jamaican Plains (might do the this week) but instead installed Gloucester which I already had in my wacky "Installers" folder. It was the version I intended to install anyway and I wanted to keep with my system of creating Windows restore points before updating SONAR on my (mostly offline) DAW. This way once I install JP I can use Windows restore to go back to either Gloucester (the new install) or to Dorchester (the version I've been happily and apparently obliviously using up until today).
Two things to report that are semi related to the topic at hand...
1) I did notice that after installing Gloucester my current project opened quicker and without the momentary "whiteout" I had been getting on Dorchester. That's nice. Hoping that maybe it'll solve the problem I've been having where Sonar doesn't release itself in a timely fashion after closing the app (I have been having to wait for a minute or so after closing before I can reopen Sonar and the time needed gets longer the more complex the project is).
2) Drum Replacer unfortunately, in this case, is not doing what I hoped it would. However I am pushing it likely FAR beyond what it is capable of. Essentially I am attemping to take a full kit stereo file (all drum peices being played at once) and isolating individual kit peices for replacement/MIDI conversion. This drum part is, unfortunately, just far too busy for that to occur it seems. There are just way too many toms, snare and kick parts all blasting away at once (think Slayer drums on meth) so DR seems to be making a noble effort it's just too many transients for it to deal with. Yes I've futz with all the Freq, Thresh, Interval, etc controls and even went so far as to try to make the task easier for the DR app by isolating the kick using R-Mix then running the resulting file through DR (I bounced the R-Mix'd version then ran that through DR if anyone is curious about the technique).
Anyway... it's not doing what I would like for THIS track but was a good experiment anyway. I think if I could get even kick + snare + overheads as source material (the second most simplest micing setup for drums) then what I'm attempting could work rather well through DR (even for crazy blasto stuff). Maybe not but I have some material setup exactly like that I'll be trying it on.
For more laid back stuff I'm sure it's fine. My only concern I think would be potential "flamming" between the originals and the samples but I also see a little vertical transient marker in the "sample" area that could maybe be moved around to eliminate that. Not sure how the MIDI export would respond though.
Just some thoughts on DR and other general crap so as not to leave this thread as a total derp dump.
Cheers and thanks all (especially scook) for pointing out what the problem was.