Downside of going mATX?

[Shadnic]

I have been planning my new build for a while, and was going to go with a Core P3 + ATX mobo+ Single GPU + 280 Radiator AIO cooler, etc. It will all fit in the P3 very easily and will be a very nicely laid out and (hopefully clean) build. With the announcement of the new Core P1 though, I realize that I could get a mATX version of the mobo I was considering (Asus Strix z270G) which is essentially identical to the ATX version just ....smaller. 

 

https://smile.amazon.com/dp/B01MTXYAB8?ref=emc_b_5_i&th=1

 

Is there any downside to going with a mATX board? Does the build feel more cramped? Is cable management harder? Heat dissipation worse? 

 

The P1 has really thrown me for a loop, I can't decide if I like the idea of a smaller case now or not. Would love any opinions or thoughts, thank you!

[warreny]

if you are going for a single gpu i dont see a problem but if you ever plan on going sli i would consider watercooling gpus. Considering how close they are could see heating issues. I have a p3 build on my wall actually wished i went with a p5 now looking at it >.<