I assumed you had maintained that order but appreciate confirmation of it, thanks. Regarding the use as you've noted anocdotally, yes i agree that that should be the case. i.e if the device can use the HERE mapset then the traffic should work [that would be all both NT capable and traffic capable devices in that case, not just 2013>]. I'll try it with HERE maps on some older units when i have time. I suspect Garmin's pronouncement below from the page i linked is to do with them having shifting from Whereis to HERE [Navteq] as AUNZ OEM map provider for automotive devices in early 2012 [2013 devices were released in 2012] and presumably HERE traffic only works with HERE maps whereas Suna is not map dependent.
Every data-ready Garmin device since 2013 will be able to tune into the new service.