Welcome to the forum.
The narrower motherboard form factor provides more room inside the computer case and this might help with smaller cases.
I've seen several ASRock motherboard reviews where they commented on the motherboard being flimsy.
For me, this rules out buying any flimsy motherboard model.
My P35 motherboard is the same size, but it's not a problem if you are careful.
I always unplug the power supply cable from the back of the computer case (or the wall outlet) before I make any changes to the inside of the case.
If I'm removing or installing any cables to the motherboard that are to the right front of the motherboard attachment screws, I support the loose end of the motherboard with my other hand so that the board can't flex.
Looking for a good forum username, how about FlexiMobo?