Makes for an interesting question as well. If someone is flying a high performance aircraft on a 61.75 certificate do they need an FAA HP endorsement?
It is a VERY interesting question, and one which I sought to answer a few years ago before I had a standalone FAA licence.
Here's the scenario - I had a 61.75 'foreign based' licence and wanted to fly an 'N' reg 300hp Cessna 206 whilst on holiday out in the States.
The SEP (land) Class Rating on my UK licence covered this (and I had hundreds of hours in a Cessna 206 anyway), but did the ASEL on my 'piggyback' FAA licence?
I could find nothing in the FAR / AIM which clarified this, so I went to the local FSDO and asked them. They said that the 61.75 licence gave me exactly the privileges of my UK licence - so I should be ok.
The flight school who hired me the aircraft though, thought that to be on the safe side, they would give me a high performance endorsement as part of my pre rental check flight.
These days I have a stand alone FAA licence so things are now much clearer.