There is no standard button layout. HS has 2 different a designs (V1 and V2), heck they may have a third one if they didn't go back to V1 layout. Vortex has their buttons, Sig has their button layout as does Trijicon. I'm far from an expert, but the ONLY worry i have about getting the V2 lay-out would be warranty issues. If you have to send it back there is little too no way they will rework a unit that is in violation of patents, so you may get a new unit. Good or bad.. who knows at this time.
I have Trijicon on my milled G19X and HS on my G19MOS. Button layout isn't a concern for me. Depending on how you set the HS up the firmware will limit what you can immediately do with the buttons. On AUTO mode you have to hold the + button down till the dot blinks and goes into Manual mode. Not doing that in an emergency situation. I usually find a useful brightness and leave it there. The AUTO tends to be too dim for my crappy eyes in almost all conditions.