scousadelic all they do is put the pipework at plinth level, if you're having a kitchen ripped out they have access to all the pipework as you should have an empty room.
A sink unit (old style Faktum, fitted last year) has a half bottom to the unit allowing all the pipes into the back of the cupboard.
Why would anyone want to waste space behind every cabinet? Drop all pipework to skirting board level.
I have had my kitchen a year, my sister has an Ikea kitchen and it is around 3 years old and looks amazing still.
We ordered in store, it gets scanned going onto the lorry, and scanned coming off into your house. We were missing 4 items (ie they weren't in stock, not we can't find them on the lorry) they arrived 3 days later. Ikea phoned me and arranged a delivery date convenient to us.
We ordered the kitchen early as we wanted to make sure everything arrived and we were having a kitchen extension built. Being an organised sort of person, after Ikea had delivered it we stacked it (keeping it flat) into larder units, base units, wall units, interior fittings, plinths together etc. Plus I wrote on every box what it was ie 600 base or door for pull out larder etc in black marker so the fitter knew what it was.
Ikea give you a full print out, so the first cupboard you started your design with is number 1 and it lists all the component parts for that ie cabinet, door and any interior fittings. It was very easy to find stuff.
We had an independent fitter do it as he was recommended by our builder and we were more than happy with it all.