I recently tore out the cast iron radiators from my house and installed a Stadler Pextron radiant heat system in my first floor area. I opted for typical hot water base board for the second floor.
The first floor area had open joists under neath so i used 1/2 tube with radiant aluminum heat transfer plates and r-19 insulation.
i had to break the loops into 5 seperate zones, but used 1 circulator.
Another option is radiant panels using smaller tubes. these panels are machined out of plywood and screw down.
i used the radiant panels in my 2nd floor bathroom because i did not want to tear out my kitchen ceiling.
talk to Eric at Boyertown Supply in boyertown, PA.