London Rob: I am coming late to this thread, but I thought I would add my thoughts. In reading your inital post, I thought that you and I are similar in needs. I have the 35 mm Limited and then in a trade bought the 43 mm. Now I have both. There is something about the 43 mm that just seems to inhibit the use of the 35 mm for me. For shooting wide open and indoors for close portraits of kids and many others it is a great lens. I may end up still keeping the 35mm, too hard to let go or an otherwise great lens. As others have said, they are just a little too close to really need both, especially if you need the money.
I see that you have made your mind up. I would only point out from my experience one matter. If you arrived at your decision because the lens(es) you buy in place of the 43 mm are truely a better fit, then go for it. Just don't let the purchase be a 'settle' or a 'better deal.'
The reason that I say this is because the limiteds have a way of 'calling' you back. Sometimes the call is maddening. Hang up as often as you like, but it just keeps you on speed dial. You need to make sure that your decision effectively unplugs the phone. You have got some great advice in this thread from some very respected posters. I like Blue's last statement regarding the allure of the 43 calling you back. I had this with the 31 mm. I went and tried it. It is a great lens but not one that I would use in my style of shooting enough to justify the cost. For me the 43 is the best limited. But by trying the 31 mm I feel I have effectively cut the phone line. There is no wonder for me whether I am missing out on the 31 mm.
I have seen it many times where a member chooses against a limited only to sell what s/he bought and buy the limited later. What happens is that we come back to the site and make the mistake of looking at images of the said limited only to see a series of killer images...alas, the phone line has just been connected.
Good Luck,
Mark