Well, the ts is essentially just a heat storage system, the ufh is a dissipation system and you thus need an appropriate generation system. A ts helps match the supply to demand; if you've determined you need to heat constantly at 10, and your boiler provides 100 then in any given time period your boiler will have run for a tenth of the time, and the ufh will have plodded along sapping the heat. The buffer smoothes put the supply

Ultimately it depends how you will use your ufh as to whether it is the right type.. Are you going to run it constantly or turn it off when you're out at work?

We have a mix of systems. Pipe in screed and pipe with heat spreader plates. Both work well but pipe in screed does take quite a bit longer to warm up those rooms.

I reckon pipe in screed and other high thermal mass systems are better suited to families with at least one person at home in the day time. If everyone works 9-5 I reckon rads or a low thermal mass approach is possibly better.

Clearly having so much insulation that heating is nearly free is even better. Who cares if the heating is a bit slow if the losses are so low you can afford to run it 24/7.

The advantages of a thermal store depend more on what is heating it. Our TS helps stop our oil boiler short cycling. Oil boilers cannot modulate (turn the flame down) like a gas boiler so they switch the burner on and off to reduce power output at times of low demand. That's a bit like stop start driving in a car.

If you have a fully modulating gas boiler the advantages of a TS are less - you might save money by using a cheaper mains pressure stored hot water tank, which are made in greater quantities, for the DHW.