IMHO. I think it's a bit clunky to not have a play start button. Every sequencer I've used had a play start button and I stayed away from those that didn't. When Opcode got killed by Gibson I refused to switch over to Performer for just that reason. (well, more than that reason)
I've had Reason Since Reason 3 but I only used it as a rack until they got blocks because I prefer pattern based sequencing. Now here I am and I find the absence irritating.
The preference for it to either. behave the way it currently does or behave like most every hardware based sequencer since the dawn of time would be great. I still haven't got used to the multiple clicks.
PT gives you the option, so does Logic and so have many other software sequencers. Those who like the resume style play button will probably not fully appreciate what it is i'm griping about. but heck, even the MPC has both.
Say yes to the one button/ one keystroke!