It does not affect the suspension. It will lower the rear fender and rear of the seat. It will be most noticable when swinging the leg over to get on and sliding way back in whoops. There is a lot of clearance between the tire and fender, so no worries there. I am pretty tall and I was still thinking of doing it for the above reasons.
If you use the bike to play ride, you can consider having the suspension lowered (spacers are put in and it will shorten usable travel a bit).
KTM claims you can take up to 10mm from the sub-frame without bottom out worry. Many will also tell you as smilin did, about spacers for the shock which restrict it from comming all the way up.
I am same height as you are and I found that shaving the heck out of my seat foam was all I needed to do. It makes the ride feel totally different, easy to mount, and lowers your center of gravity which is a plus. I used a hacksaw and cut all I could get out of the TOP of the seat. It will make it flat and not a comfortable ride for trailing, But if you MX, I feel it's the way to go before you do any sub-frame shaving.