Modification later in life will be a big zero. I like the noise proof...that is really cool. A friend lived a few years in the ICF house below me and quiet is where it's at...also, if this project moves forward this year and I build where I want to the wife won't hear me shooting out the back door.
I just said inuslated, the windows and doors are where most of the noise comes from anyways. True comm'l quality windows is what you want to keep things quit inside. When I say modification later, I'm not talking about major remodels, I'm talking about dumb things like, I want a cable outlet here, a plug here and etc.
ICF are alot like SEP, great for the builder, but not so great to live in.
One of the good things about ICF, is for the most part, they can be installed by some one that is realtivly unskilled, but can read and fallow instructions( you would be amazed at how many people can not do that)
As too the steal raftors and the like, They are actually weaker then properly done wood trusses, they also cost alot more. With the proper storm ties, all the correct nails and other fasners. you will be fine. One thing I would highly recomend is having the ceilings supported by the walls and independent of the truss system. That way you have less chance of cracks forming.
If you are going to dig out for a basement anyways, i'd look into a prefabed concreate storm shelter. The modern prefab stuff is very good, its even out they make bank vualts.