As with most things in the building industry - most trades and builders don't like anything that is slightly left field. They want something tried and true and just bang them out like a cookie cutter. You will need to patiently hunt around for someone who is sympathetic to your requirements. You may have to pay a premium for the hassle of getting someone to coooperate. Perhaps the manufacturer knows someone who has used their product.
The polystyrene probably has better R values than most other construction systems simply because of its thickness. But strawbale is streets ahead - inch for inch it is the same as a insulation batt. Imagine a batt 1 foot thick.
Whilst the concrete is structural in your proposed ICF, you are hardly getting any thermal mass benefit because the internal leaf is covered with insulation. If it was exposed internally then it would function much better.
At one stage I considered a more useful concrete formwork solution to allowed you to pour an in-situ concrete wall. It puts the insulation in a better place - sandwiched in the concrete. There are also pre-formed conduits to chase your services. It seemed reasonably cost-competitive to a block wall.
http://www.formatech.com.au/
On the subject of eco construction materials, I have seen Durra Straw pre-fab internal wall panels. It's an engineered straw wall construction. Very dense, thermal and acoustic insulation, strong and self-standing (nail to top and bottom plate). It is also environmentally friendly because it is from a recycled product. The only drawback is that you are limited where the conduits for services can be placed and the panels come in set sizes that may need to be cut.
http://www.ortech.com.au/durra/durrapanel.html