So - maybe group 1 all same time start, all other groups - as you cross.
Probably too much fuss for the timing people, but given the profile of the event now (XCM series, the prize money, and the TV coverage), you wouldnt want the chap crossing the line 2nd actually winning the race overall.
Interesting though that the people taking more time on the course are more worried about 2 or 3 seconds (or even a huge 30seconds) at the beginning.
Still - everyone takes different things from races, and what suits an Elite rider is often completely different to another rider.