UFH in Cupboard Under Stairs?

I have a fully operational 2-zone wet UFH system in the ground floor of my house. Suspended floor with PIR boards between joists, pipe laid on top in a S&C biscuit screed.

Builder ran the flow and return for one of the zones under the joists of the cupboard under the stairs. The stairs go across the house left to right. Old victorian 2-up-2-down.

Before I lay the engineered wood floor, I'm debating whether to move these pipes above the joists and heat the floor of the cupboard like the rest of it, or whether it's better to just lag them and leave them underneath. Wondering whether it's a good idea to heat an enclosed cupboard like that or if it would just be a waste of heat. Maybe it would help keep the timbers warm and dry, preventing decay. Any suggestions?

 

If you ever use it as an airing cupboard, a bit of heat is useful.
If you ever use it as a larder, you want it cool if possible.

If the pipes are below the PIR, make sure they are well insulated.