I wrapped mine when they were off for the engnie refresh (as the the bolts ALL had to be cut off along with the brass studs!). I typically bought cheap wrap it seems as he does steam a bit on these cold mornings, but I have to say the engine compartment seems a bit cooler.
I am thinking of maybe finding some thermal gaskets thought in the Spring, just to stop too much transfer of heat to the head. I know this is an issue with eth K-Series I have, so assume it's a general issue. Although as others have said - in the UK climate it's less of an issue.
1998 Range Rover 4.6 HSE in Oxford Blue - Inherited from my Dad
2004 MGTF 115 in Starlight SIlver with Red Power Roof - My toy!
2004 MGZS Plus Facelift in XPower Grey - just acquired.