I'm using both S1v3 and Plt. I recently moved a midi project out of S1 over to Sonar and I find it somewhat, unpleasant but doable.
 
The Instrument tracks (midi) in S1 uses a system for CC info that is scaled in percentage vs. actual 0-127 values. So, a CC value of 80 in S1 is approx. a value of 102 in Sonar Plt., Kinda... That aside.
 
I feel Sonar's PRV allows the easiest editing of Multiple midi tracks but working with CC's and automation still has issues that should have been fixed long ago in PRV. I also get inconsistent timing issues using Sonar's midi and sometimes I can see where notes have somehow moved on the timeline. I have wasted a lot of time on this.
 
S1v3 has a rock solid midi engine but editing Multiple Instrument tracks requires a bit of getting use to. I really don't enjoy trying to switch a project/song between the two DAWS.
 
Both Daws have their midi strong points and both have their drawbacks. Sonar could be the Solution and Only Daw for me if they would just fix some of the long standing PRV issues. I really enjoy starting a midi Project in S1v3 because the timing is rock solid and I really like the new Arrangement features but I would not want to try and move every project between the two. I am still weighing the benefits of both but currently S1 is winning and my frustration level of Sonar continues to grow.
 
I realize that I am not the only Sonar user but if they would spend more time improving controller editing in the PRV vs. a New start page, etc. I would be more inclined to Stick with Sonar.

I use a few things, besides sonar.. cubase / s1 and reason.. each thing I use has things I like.. 
 
it makes it easier if you don't use "locked in" plugins.. I tend to use things that are unlocked and work in everything.. fabfilter plugs or ozone for a start.
 
it partly depends on what you use / work with. for example you can export midi easy enough and dry audio.
things like samplers.. I use TAL sampler as it's accessible to anyone (due to cost)  vs say Kontakt libs I use
 
 
 
 

Great thoughts, rtucker...helps a lot.  I've decided to forgo the labor day sale upgrade for the moment as time is precious, gardening is consuming a lot of my time at the moment, and after investigating a bit S3's track template workarounds are very kludgy and I'd really spend a lot of time recreating my setups while preferring to concentrate on songwriting, which is slick, quick and fully ingrained in my brain with Sonar's template system.
 
Maybe I'll revisit the issue during the rainy season when more time is available... then again, we might get an "arranging" system is on the horizon indicator which would be my fondest wish.  
 
Thanks, all for chiming in.  You've really helped me weigh the pros and cons... and given my desire to create rather than ponder "now how do I do....." I'm gonna forgo exploring other possibilities at the moment.

Congratulations Vastman,
 
It sounds like you did your research and made a conclusive decision, at least for the interim. It sounds like you now know your direction, have saved some money, and, will get some songwriting accomplished. Best of luck!
 
Kind regards,
Rick

MachineClaw
Sonar for prime DAW, I think I know it the best.
ProTools 10/11 only because of 11 rack hardware.
Live 9 suite because of max apps and looping stuff
Cubase 7.5 for midi and hardware midi devices.
Reason 7 for some of the reason rack extensions and some Rex library stuff I have, works best in Reason native.
FL Studio 12 for piano roll easy midi /loop stuff and painting notes really easy.  I use FL Studio more than Live now.
 
so to answer your question, no it's kind of a pain in the ass going back and forth between DAWs.
 
but it all depends on what I am trying to achieve.  Each DAW has it's different work flow and does some things really the best.  not 1 DAW I have has all the workflow or functions I love and need the most.  I have to use multiple DAWs to get what I want done some times.
 
generally I just export stems or WAVs and import into Sonar and then mix play in sonar.  if it's just straight audio like vocal or guitar then I generally just stick to Sonar.  All depends on what I need to do.

 I like this post. Usually exporting stems works best. Midi sometimes has problems.