It goes beyond "not" fun. It's dangerous. This weekend we had MWF40 AM gridded up in front of ULWSBK EX. Like Apriliaman said, we were in them by turn 4. By turn15, I was in the lead pack of three ULWSBK when our first two passed a MW bike in a borderline maneuver. I could not get by. Not only did I almost run into the MW bike in 15 as he cut me off from my pass, but I did then actually touch his rear wheel (after a panic brake on my part) as I entered 16 still stuck behind him when he did not maintain his speed (as is normal) but instead hit the brakes from his already turtle-like pace! By the time I got by him, the other two were a good 3 seconds ahead. This is all on lap 1 mind you.
I did some analysis of the lap times for that race. Here they are:
Fastest Lap Average Lap
Winner 1.38.552 1.40.194
Slowest 2.01.990 2.02.842
Winner 1.35.657 1.37.315
Slowest 1.43.748 1.44.742
As you can see, the lap time disparity is ridiculous. The slowest Ultralight is 18 seconds faster than the slowest 600. At the same time, the fastest Ultralight is 3 seconds faster than the fastest 600! This data clearly shows that the race order should be reversed at the very least. Starting the ULWSBK behind AMs on 600s is a bad move.