In TR’s version of the 20min test, the 5min “all out” is @ 110%; not so anaerobic. Doing 35min @ 100% could put a “tired” spin on the last 20min of the hour ride, especially in my current state of ‘how low can you go’ fitness.
After consulting with both HR and RPE, I’m going to go with a new 240 FTP. 
(which is weird after such a prolonged period of inactivity…
oh well…take the money & run!)