Just to clarify, the use of collar beams or joists between rafters is common construction. The open cathedral ceiling requires a ridge beam to hold the upper end of the rafters in place. This is clearly a structural member and is different from a non-structural ridge board.
Speaking of variations, in my current house the roof is hip-framed using I-Joists terminateing on ridge beams with large doubled jack rafters on the hip. There are actually cathedral ceilings for the kitchen and living room that are separately framed inside the attic envelope. You can stand in the attic and look over the framing for these ceilings. Pretty complicated.