Good going GenCon.
This year was great. Letting people know their times in advance was wonderful. Pretty much the best implementation of a random lottery system style of fairness possible. Sure there is some tweaking to be done, maybe a little more guidance and advance notice to those seeking ADA rooms, but otherwise, a good improvement.
Keep it up. As systems go, this is my number two option out of many, and it looks to me you are implementing it well.
Just wanted to send a positive note in the midst of the many temper tantrums out there. they'll get over it. Or not; looks like you'll easily replace those that don't. You can't make everyone happy, especially the unreasonable. The current progress you are making, and use of Indy are the right choices, as shown by the convention growth. Good luck managing success, as that can be rough.
/A pleasantly surprised customer