I'm co-sleeping with DS2, 7 weeks. It is a nightmare.
I thought it might be the secret to peaceful nights, or at least more relaxed feeding, remembering the hours spent propped upright with DS1.
It is not. DS2 is not a happy bunny.
He has terrible wind and writhes in pain and farts after feeds. He may drop off to sleep on the boob but then five minutes later, just as I'm drifting off, he's awake and furiously in pain. Winding him doesn't make a difference (aside from waking him up good and proper). Really, he wants to sleep upright on a chest, but I'm terrified of dropping him as I fall asleep myself. Also, it's bloody uncomfortable sleeping sitting upright!
And I wonder, as I'm pacing him up and down in a baby carrier at 3am in the living room so as not to disturb DS1 and DH, does he even like sleeping with me and feeding lying on his side? He often seems so pissed off! He shakes his head at my nipple (yes, he may well be 'scanning' for my breast but he is so ANGRY with it) and flails around (with his sharp claws fingernails, ow). He pushes me away if he's fed up and seconds later is groping for me again. Sometimes he glugs away but mostly he's not settled by feeding like this, and I have to sit up anyway and feed him more conventionally. (Have also tried Biological Nurturing - it settled him a bit initially but not now.) His weight gain, nappies, etc are fine, btw.
This afternoon, I left him sleeping restlessly on the bed where I'd been trying to nap with him (propped up safely on his side with a rolled receiving blanket), and had a shower, thinking he'd be roaring in minutes. No - he actually settled into a deeper sleep for about 40 mins. Without me there! 
We always presume they want to sleep snuggled alongside us and that any option involving a cot, basket etc, is going to be complained about by the baby, at first in any case. I'm just wondering now - does he actually even want to be in bed with me? Does he want to feed lying down? 
(I should point out that I'm also at the end of my tether in terms of sleep deprivation (4 hours a night if I'm lucky) and with walking up and down every night, and with trying to keep 3 yr old DS1 ticking over during the day while juggling an un-put-downable baby. Just to put my crisis of confidence into context...)