My Garmin made it 5.9km as the foot falls, incl 0.3 for a backtrack for that overgrown track at #4. Climb (which I find it under-states) was 215, so you could well be right with 280. Nice run.
I counted contours crossed on my RC but it's quite possible I may have mentally added 50 rather than 25m on one of the longer uphill stretches!
Heh heh. Thanks for referencing the map file. Was pleased to notice (for the first time) that Condes automatically breaks connection lines for the control numbers.