I agree with your comments about Beginner MTB racing. I raced in my first ever mtb race two weeks ago in the sport class and was absolutely destroying the field until a mechanical. Even the sport class seemed slow and out of shape. Technical skills of the top sport riders were a tad better than mine probably (I never witnessed them), but their endurance was minimal. I also approached this like I would a cross race (the first mile or so was fire road) and just nailed it from the whistle. After I created a big gap I just rode tempo for most of the double track areas and rode cautious in the single track. I dug deep in certain areas where I figured the mtb riders would be dogging it. All in all the race was fun. I love to race cross and have done fairly well so far so I think this will help me improve my bike handling skills until then. Anyway, move up to sport, I don't think you'll mind the challenge.
RB