Nemo, you might find this site useful:
www.slingmeet.co.uk
If you can get to a slingmeet you would have the chance to try out different types, and save yourself from making an expensive mistake.
Though if you do, slings hold their value very well and you should be able to sell it on for a fair whack of the original price.
I have a younger, but very hefty baby, and I use a soft structured carrier and mei tais for out and about.
The carrier I use (and love) is a Sleepy Nico, available from:
www.sleepynico.com
It's very comfortable, incredibly easy to put on and very pretty. I'm not very generously endowed in the boob department, but I have a friend who is very curvaceous, and she finds her Sleepy Nico very comfy too.
BabyHawk mei tais are also comfortable and pretty but, like all mei tais, the straps are so long they end up trailing on the ground/floor when taking them on and off. But that's the only downside. In the UK you can get them from:
www.snugglesnooze.co.uk
and
www.bigmamaslings.co.uk
and I expect there are other dealers if you google.
You can also get a wider range, or even custom made, by buying from America at the BabyHawk site:
www.BabyHawk.com
But, if you do, you are likely to get stung for import duty.
If you want to back carry the Calyx soft carrier is the best and easiest I've seen, (and can be used on the front too). But it's only available from America at
www.mamagear.com
And I know other people swear by woven (not stretchy) wraps for bigger babies. But I haven't tried them (yet)!