Painting a metal roof

We have a rural "A" frame cabin we've been fixing up for about a century now (OK, maybe 3-4 years), and we're close to being finished. One of the cosmetic unattractive features of the place is the roof color, which is kind of a power or sky blue. Very 70's, which is of course when it was built. We've been thinking a medium grey or industrial red would be more suitable.
To complete a stovepipe repair, I had to paint one of the roofline dormers that stick out on each side of the "A" frame. I washed it down, applied a light dusting of spray primer. We got a good color-matched metal paint and I painted the whole dormer roof with a paintbrush. It took longer than anticipated, and once the sun hit the roof it was tough to get the paint to go on smoothly. The job was still pretty good, although the finish of the paint is not uniform across the section.
Seeing that the results weren't too bad, I am now wondering about painting the entire roof, probably 1200-1500 sq feet of metal. It is mostly in good shape, the area gets little precip and the roof pitch is very steep. I would likely hire it out anyways, I look forward less and less to spending my weekends on a 36 foot ladder, and I'm betting pros would spray instead.
Assuming a good prep and paint, how would the result compare, durability wise, with the original baked coating? As mentioned, there is little precip and the pitch prevents any snow accumulation. I am most concerned that the paint application would need to be limited to time windows of early morning or late evening to avoid applying to hot metal. Also, a layer of paint might peel or bubble given the extreme heat it would ensure in hot dry summers.
Anybody painted a metal roof before and have any advice?
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