I知 afraid I can稚 provide much guidance in that area, as I did not price it both ways. The truth is I decided on using the Faswall block before I even had the plans complete. Again, for the DIYer with time and some good help during the critical times of pouring the concrete, I think there is an argument to be made the blocks are a cost-effective method yielding a superior building over stick-framing. That argument goes out the window when hiring a contractor who has no experience with the product.
One thing to note when comparing Faswall (or similar) blocks to standard foam ICFs. While they are obviously similar in design and construction, there are some fundamental differences. Foam ICFs yield a conventional building envelope which places a high value on being air-tight. Faswall blocks are designed to create a wall which is vapor-permeable, acting not only as a thermal mass but also as a humidity sink, maintaining a more stable indoor relative humidity. Additionally, Faswall blocks are more efficient as a thermal mass because the insulation is all on the outboard side of the concrete core. A conventional foam ICF generally has the same thickness of insulation between the concrete core and the inside of the building as it does between the core and the outside, which significantly impairs the flywheel effect of the thermal mass.
My location is in an area with timber and high risk for wildfires. And it can get VERY WINDY. I chose the Faswall blocks (and exterior Roxul insulation, steel framing for the decks, metal siding and roof, hardwood decking with a Class A fire rating, etc.) because I wanted a structure built like the proverbial brick sh*thouse and as fireproof as I could make it. Those considerations obviously added some significant costs to our project.
