No real advice, but just wanted to say my DS also has a real cot aversion (seems to be the sides) so he is now on mattress on the floor (no good for you while pregnant) and is also a horror to get to sleep (he pokes his eyes to try and stay awake!) but I did exactly the same with him as did with DD, and he is so opposite in sleep patterns to her - so you can do the same and end up with complete opposite - so if you want to co-sleep (we have always done on and off) with number 2 do it - better you do what feels right and you may or may not end up with a difficult sleeper - than do something you are not so comfortable with and still end up with the same result.

I am sure also have read a few times about where number 1 child has started sleeping much better right when number 2 arrives - is like they have a sixth sense or something about how much you can cope with.