Thank you very much for your answers! I've used the rims since Aug 2010 and only for daily commuting 1h a day in total. And actually I asked the question about discs before realising how expensive they can be
For a set of A719's I paid something around 160 GBP ($250). Would you say that it's more cost effective in the long term to buy discs and curb rim wear? As for being set-up for using discs I'll be getting the Planet X Kaffenback frame so no problem with that.
PS: I've just found a good deal on A719, possibly I can reuse my XT hub after some cleaning but what spokes would you recommend?