Hello Darren,
I can vouch for it getting hot on diesels. I have a Sealey master compression test set which I used the right angle adaptor from to join to one of the spare adaptors that I got with my WPS, so that I can use all the adaptors in the set. The wps has saved me having to strip a head off to check for valve damage when the timing belt failed on a renault Trafic & I have used it several times to confirm correct or incorrect timing on various others. For the benefit of others who haven't yet got one, It's also been good analysing fuel pressure/injector faults on diesel as well as petrol, pump faults, air compressor faults, turbo charge pressure & i've even used it to confirm tyre pressures.
Regards, Andrew