Happy to report that I was able to complete the client session tonight with superb stability and indiscernible latency while tracking.  I used the WASAPI driver model and even with several "CPU expensive" processors enabled had completely clean 3 msec / 144 sample buffer.


There are a few minor quirks in this mode such as the Audio engine stopping after 5-10 minutes of idle time, but NEVER during use.  It's a nag that can certainly be annoying while i'm working in the vocal room getting a client situated and dialing in mic placement etc. but easily remedied.


I'm finally getting to go through the session and found a few odd "when did that happen" situations, mostly to do with pro-channel modules. 


The default channel-strip (at least for my system since I had never changed my default):
  Compressor > EQ > Tube > Console Emulator
All of these modules were enabled on EVERY track even though I only had maybe a handful of ones I had actually utilized and changed.  The Channelstrips themselves were disabled but when I had the project playing the activity lights definitely registered signal was passing through.  I went through and manually deleted every module in the channel-strips that I know I don't want / not being utilized.

Currently exporting renders while in WASAPI, and then I'll try switching back to ASIO to see if I can find what was causing the memory leak.  I noticed when I export it says processing audio - but I'm positive I've never enabled audio snap, used audio stretch tools, or have any vocalsync or melodyne clips still "live".  What else would have to be processing before audio mixdown occurs? 

I've opened the project up now back in ASIO (1024 sample buffer @ 48/24) and the memory leak started climbing.  I tried bouncing some clips of some already frozen tracks that I had chopped (not stretched or anything else) and somewhere in those bounces the memory leak apparently fixed itself.  I hit undo on each of those edits I made to see if the memory leak would start happening again - hoping I could find which track/clips did it.  Nada.  Exited without saving and re-opened.  No more memory leak, but i'm still stumped!

At least now I can finish working on some of the production elements before I prep the project for mixing.

UPDATE:
Alright, I'm about ready to package up a CWP file for the support team to analyze because the Memory leak and static creep are BACK when in ASIO mode (again, same project).  I just had one more recording session in the project this thread was posted about to get some touch ups done on the vocalists' harmony work.  I had opened the project several times in the last week since my previous post which it was working completely fine in both WASAPI and ASIO mode after doing all of the previous things I had thought fixed the problem.

All I did was open the project to bounce various mixes (not even using mix recall at all), and I open the project up today and immediately experienced the issues.  Not having time to fiddle with anything I immediately closed the project and reconfigured my preferences for WASAPI and my lowest tolerable latency settings and was able to track no problem.

During the weekend I received and installed the new parts for my PC, 2 more sticks of the exact same model RAM to max my memory out at 24gb (the motherboard is an ASUS P6x58D Premium that's over 7 years old).  I also installed a SIIG PCI-E Firewire card (confirmed TI chipset) and disabled my onboard VIA firewire chipset and proceeded to open up numerous projects.  The firewire 800 bus works flawlessly, Sonar seemed more stable initially:

ie: prior to the PCI-E card, Sonar's audio playback and visual display were always noticeably off (we're talking between 200-300 ms out of sync). With the Texas Instruments based Firewire connection, the Fireface was recognized instantaneously as opposed to a few seconds later by windows - and the RME Total Mix software popped up the fastest it had ever popped up when I power the unit on.  Sonar's audio playback and visual display are noticeably more in-sync (near perfect if I can be so critical as to judge).

However, today was my first day back into regular production level work with Sonar and it appears the issues have returned.  As soon as I'm done editing, I'm creating a completely new empty project, and carefully rebuilding it with raw bounces and/or instances of the Virtual Instruments... Not exactly how I expected to spend my time prepping for mixing and mastering but I simply cannot live with the memory leak and static creep (nor do I prefer to work in WASAPI).