One 'early plant' case I've seen recently was where a defender died just after the doors went down, left his spawn and stood in the middle section by the edge to watch. A knight on our team who was quick to the scene jumped to him across the gap, pushed him into the void and capped the door - all before the bridges had gone down.
Nothing at all 'dodgy', but OH the wailing and gnashing of teeth.
Also I've never seen anything that looks even remotely like hacking from Physics, so lets not go there. They're just good. Most of them
I honestly haven't seen anything that couldn't be explained by lag or abilities in MONTHS. I got angry a little while ago when some marauder kept hitting me with melee from what looked like 20 feet away - but I know it was just server sync issues.