I agree with the above statements about not making major changes with the transport running.  However, I've had Splat crash on me a few times while inserting Rapture Pro without the transport running.  I've tried to reproduce this several times, but failed, so it seems to be a random act of nature.  Yet, it only happens with RP.

However, this begs the question that if this is clearly something that can affect system stability, then shouldn't Sonar block the action while the transport is running?  The responses above, while helpful, seem to suggest that it's OK for Sonar to crash in this instance and I should know better. . . am I misreading this?

+1, or even stop the transport, replace the synth, and restart it.

rlared
However, this begs the question that if this is clearly something that can affect system stability, then shouldn't Sonar block the action while the transport is running?  The responses above, while helpful, seem to suggest that it's OK for Sonar to crash in this instance and I should know better. . . am I misreading this?

Sonar can actually take quite some abuse and still works fine i.e. you can insert/delete/change FX while transport running (does make sense and I wouldn't want to miss that!!) and actually inserting/deleting/changing a VSTi is not so much different apart from it being harder on your resources (e.g. loading samples,...) although VSTi change I rarely do ...
 
Occasionally I push it too far and get a crash - and most of the time it's actually caused by the audio driver giving up (which I can see from the crash message). So with some drivers more stable and mine not being the best (Roland), it's still working and I would not want to be restricted upfront ...
 
 

I never based my decision about not doing things while transport on any experience of having such a thing causing any crashes.
 
I only reasoned that it would be a POTENTIALLY crash-prone thing to do.
 
I cannot speak for anybody else on that notion - it was just how I always saw it, and besides, I am quite deliberate in how I approach making changes to things, and having the transport stopped while I am making changes is quite inline with how I approach it all.
 
Bob Bone

Fair enough. I suppose I do need to consider that the system is performing real time calculations when I make changes, so a mindset change will help. No more changing synths while running the transport!

reminds me of a quote from one of my favourite movies
 
"Never changes horses in midstream"
 
... though I don't live by it :-)