Have you used these before or seen them. Was looking into it and actually seen them advertising on Facebook but there were a few issues people mentioned about this product.
Used it back at home, it's only available in the UK via a merchant called eh smith, their prices are not competitive whatsoever because no-one manufactures it in the UK it comes from germany, but you can pick it up much cheaper in France and get it shipped to your door.
Although it cost more than cavity construction on the material side, the savings you make on labour is massive as it's rapid, also their biggest block in theory you don't need any ewi as it's u value better than the current regs, so you saving on insulation as well.
It's only thinbed mortar and blocks are interlocking, you can throw up an extension in a day if your first course is set out in normal muck the day before. The mortar comes with the blocks, it's premixed and all, just add water and off you go. Some moans about it as it's a hollow clayblock and find it difficult to fix to it.
It's dead easy to cut and chase and lightweight.
Their biggest block is 65 quid per m².
If you need any further information I can pass on the reps contact details who's local to me I'm sure he's happy to help you. They also do courses it's free! where they show you the basic principles of how to work with it, plus you can purchase the hopper feeder for 20 quid to lay the thin bed mortar.