Very interesting idea. It is so hard to find competent workers down
here, at present there is no official DAC-ART builder w/ his own crews.
Plus the houses are going up in various locations in different states,
not a cluster of localized construction, so usually entirely different
crews, and it is usually their first experience w/ the product.

But the problem seems universal down here that workers choose to not
look at the plans as they go about the day. The result is a re-occuring
headache !
To run water thru the walls, whould take a really conpetent & constant
level of supervision....any leaks would be verrrrrrry difficult to deal
with after the blocks are back-filled.

However, a perhaps useful addition for thermal management is to drill a
well and circulate water in PEX pipes though the blocks. Well water on
the Gulf Coast will be roughly 70F. Water can then either be
reinjected to another well or drained to the surface.