I'm currently playing medium, but finding it a bit easy to be honest. With the exception of the story missions where you have to fight, so far I've been able to complete all but 3 missions stealthy with out fighting. The magical dispose body thing is part of why it's easy, so I decided not to use it and instead I was just going to pick them up and hide them. I discovered last night that this is not possible. You can only use that to pick up agents, enemy or friendly. It doesn't work on guards or civilians.

Since hard mode doesn't have the dispose body feature, are you able to pick up and move guards and civilians to hide them? If you can, then I may switch to hard mode, but what else changes in hard mode? The manual or game doesn't say, other than hard mode doesn't have dispose body.

Unfortunately you can only move enemy agents you've taken down - civilians and "normal" enemies like guards cannot be moved on hard mode.

I think you should try it anyway though - it's often possible to take enemies out in such a way that they can't find the bodies (typically because they're too dead), and if someone does spot a body and activates combat mode, it's typically still pretty easy to do the mission without coming close to taking casualties.

Especially with support - as you unlock more slots and you craft more support elements, the game actually gets easier. This is exacerbated by the fact that your agents still magically teleport when assaulting a place, so it's really easy to field a full team + support elements for every mission. Actually even without this it wouldn't be that hard since I'm currently forcing myself to only use agents physically at that location for missions, and I've only rarely had to do a mission with less than a full team + support.

I'm not sure if enemies level up quicker in hard - I would think so - but apart from near the start of the game, I've rarely encountered an enemy I couldn't take take down. Once you start unlocking compounds for body modifications, it's really easy to get agents with higher health than all enemies (plus extra AP and FP if you do it right, which is pretty cool - the enemies get similar upgrades at least).