I’ve used the apps to find LT1 @ 0.75 DFA-1a. This gives me a consistent HR number for LT1 of 154bpm (max 187), so of course power at that HR can vary, but it would usually be about 15-20w HIGHER than my Xert LTP.
Today Xert says 192w / FTP 255w
154bpm would usually be 210-215w ish for a typical ride (but obviously varies with environmental and fatigue vairables etc)
WKO says 263w mFTP
Today I rode 2hrs easy z2 around 150-180w and the last 30 mins I rode low cadence 210w and it felt pretty easy. Stupidly forgot my HR strap in a rush to get out the door, but HR was less than my estimated LT1. I could easily have ridden that another hour if I hadn’t run out of time.