Ditto ~ 9 years ago. I also decided to just layer over, since the original wasn't yet leaky.. just nearly denuded of epidermis, from solar flares. Worked with a local guy; thought I should find out how this stuff is done. Much sweat equity.
One pesky thing I hope you don't find - turned out that the fascia boards were too thin to properly maintain roof stiffness (as in, a birdcage Maserati space-frame?) as well as deteriorated. We renewed them all around, with those handy biscuits + glue at angle changes. A certain satisfiction of cabinetmaker kind, along with careful priming, including all hidden surfaces.
You could tell just walking on it - the effect of the restored 'space-frame' on general feeling of solidity. Then too - the mindless satisfiction of keeping all the edges straight within a 1/32", just for Fun. May yours provide some opportunity for over-building too ;-)
1.5" here in a bit over 1 day, yesterday; also a recent record for this month. Happiness is that snug (& smug).. WTF do I care? - that roof's for the Ages.
Ashton, roofer 3rd-class