I love my hug a bub, but I didn't have to pay for it (gift from my mum). We had a baby bjorn with ds1 and I hated it, it just hurt my back too much. The hab though I can use all day without it hurting.

I haven't tried the feeding position personally, but have seen pics of it - have you looked at the hug-a-bub website? It has a photo gallery on it.

As for sizes, it's pretty much one size fits all as you adjust it's tightness as you put it on. There is a larger size but I think they say that's for size 18+.

The only thing I don't like about it is that it does take a while to get used to tying it. I tried 3 times at home before being brave enough to put ds2 in it. Now I'm really good at it and can tie it quite quickly, so it just takes practice.