I have just finished setting up a Sonar 5 template file which contains five DXi instances of JABB. Other than somewhat slow load times, everything seems fine (since you had me uncheck "Zero all controllers"!).
This weekend, I downloaded and opened your incredible Gary Lindsay song Sonar 5 demo file. I noted that you used four VST instances. The demo played flawlessly without me having to do anything more than hit the spacebar!
Since you ARE the JABB, should I be re-thinking my set-up? Is there an advantage of using JABB as VST rather than DXi? As you know, Sonar supports both.
My basic system is a P4 - 2.4 GHz, 2 Gb Ram, Dakota audio card. I also run GigaStudio 3 via ReWire.