I've done an Endurance race on a 600rr it was 4hrs and 3 riders. Doesn't sound like much but i sure was bagged by the end of it.
In England and some asian countries there are some scooter endurance racing going on. The way i look at it is racing is racing. It only gets boring when the field is to small. Look at GP's best bikes in the world and more often not the most boring races to watch as there are only a few people out there.
Being on a 250 would be awesome if there was 20/30 people on the grid. Imagine piling into the 1st couple of corners 3 or 4 bikes wide.
So yeah. If the field is big enough why not give it a go?