You sleep differently when you co sleep. You don't get so deep into sleep for some reason, I think (may be wrong) so when you are woken it is not such a shock to your system.
Also you don't have to leave the bed if you breastfeed - you just sit up a bit or once you're used to it, you turn sideways and feed lying down.
I haven't got any experience of co sleeping with a baby and a bloke, as I always shared my double bed with each baby alone, which made it very easy not to suffocate them. Plenty of space.
There was massive pressure from HVs and so on not to co sleep - they literally told me it wasn't allowed - that was awful to feel I was doing something against their advice. But I ignored it having read about sleep apnoea in small babies, which ds3 had - and the way that having an adult next to them helps them regulate their own breathing.
Ds3 would literally stop breathing for maybe 15-20 seconds in the night and surprisingly, I would notice the silence and wake myself, and had to blow on his face for him to start again. This happened a few times, the GP said it was therefore too risky to co sleep, but I knew from my research that it was far too risky NOT to. He needed me to be there to blow on him, or goodness knows, he may not have started again.
He still sleeps with me now at 2y2m, I co slept with the older two till they went to school and/or the next baby arrived and they got fed up with the wriggling and stomped off to their own bed 
I would never do anything else and our cot-bed has had very little use! But will be good as a transitional thing perhaps. The older ones always want to use it when they are too big for my bed 