This is plasterboard ---

Is there any downside to using 2 sheets of 9.5mm on studwork walls (will
be skimmed) vs 1 sheet of 12.5mm?

I have relatively little wall to cover compared to ceilings and it would
simplify ordering and storing to work with one type.

And I could overlap all joints in the 1st sheet which seems like a bonus.

Just wondered if there were any major downsides?