In reason,when you play a song and stop it then play again it will resume playing from where it stopped.That is standard play button behavior.
A play/start button lets you play from the start of a song or start of a selection every time.
In reason if you double click the stop button then hit play OR if you click the left button of a set loop then hit play OR if you hit the number3 then hit play you are doing what a single playstart button does.
Play/start also indicates the behavior without the button. What I mean is this;
In Reason, if you hit the space bar once, it plays. hit it again it stops. hit it again, it resumes playing from where it left off.
In Pro tools(if you have the prefs set)You hit space bar once it plays, hit it again, it stops, hit it again, it starts over from that selection. That's play/start behavior and I would like the choice of doing that with ONE CLICK.
When I stop something, it's usually because I need to go back and listen to something that just happened like "Whoa, was that chord clashing with the bass?"
Additionally it would be great to be able to highlight a couple of bars and be able to play loop from there instead of having to set the loop points each time. Highlight bars 7 through 13 and it loops there, highlight another set of bars, and it loops there. Easier. But don't eliminate the current loop function. that could be used as a more permanent one and the selcct/loop one can be used for temporary loops.
I hope I'm clear what I'm saying....public education.
Here's a few play start buttons.