Hi trafficpat,
I too am planning to build soon and was very interested in ICF until i got a quote, i was prepared to spend a bit extra as i believe it is a good system but the quotes i got back so far are too expensive.
One company offered a complete package from external walls, internal walls, floors and an insulated roof, the price to supply and build was around €155000 for the lowest u rated option.
To supply the ICF material only for the external walls alone was €28000 and thats before training, readymix, steel and extras.
I will shop around to see if i can get some more reasonable prices on ICF but unless they are alot better i will be sticking to cavity wall, im thinkin of a 6" cavity wall that i will pump with insulation and also put insulated boards on the inside of the external walls.
Best of Luck with your build