I see what you mean and it all really comes down to price and running cost I guess. Any undesirable loss that can be avoided and using the most efficient system is the design approach I would always advise though.
You want to get someone that is well versed in UFH and overlay systems specifically. These systems can be built individually whereby the EPS overlay boards can be one component, the manifold/pump/valves/controls etc can be another, the pipe (16mm PEX) another but that is all part of the overall design taking into consideration ceiling heights, floor coverings etc which is impossible to advise correctly over the internet I'm afraid.
You want to get someone that is well versed in UFH and overlay systems specifically. These systems can be built individually whereby the EPS overlay boards can be one component, the manifold/pump/valves/controls etc can be another, the pipe (16mm PEX) another but that is all part of the overall design taking into consideration ceiling heights, floor coverings etc which is impossible to advise correctly over the internet I'm afraid.