I am really glad you to hear you say you realize the Reaver is a problem. What was the rational behind allowing it? Those who are in the running to win the gladiator can tell what it will do just by a thirty second read of the rules, so most everyone brought one. The worst part however is that reavers make the game mindless. You can look at the lists, look at the scenario, and know without a doubt who will win 99% of the time.
That being said, I came in third with straight codex marines

, (superheavies are for cowards!) and first round I defeated the flylord list (they all had the same army, almost point for point) that ended up winning, so it IS possible, you just gotta play your *****s off. Sadly I didn't get a shot at Jwolf round 4 and no one else stopped him

.
The reasons it is too good is simple, strength D weapons, 8 templates worth! Strength D is not appropriate for "normal" 40k games. It was designed by GW to make titan weapons cool and measurably different from your usual demolisher cannon leman russ. They make sense and are fun in a friendly apocalypse game with 30,000 pts on a side, but they do not make sense in a competitive environment. I think you have a few options to rebalance the gladiator for next year:
Don't allow reavers, other units with strength D are awesome, but not as broken as the reaver.
Take out all units that have strength D weapons.
Allow all units, but don't allow them to select any strength D weapons.
Redefine what a strength D weapon does for the tournament. Perhaps count as strength 10 AP 2 ordinance wpns, no +1 on result table, no ignore cover. (could also make em ap 1 and thus keep the +1 on result table) Nine of those is still all kinds of nasty, but it won't wipe out armies in one turn. This would also make other titan weapons worth buying, so you'd actually see some variety in weapon load outs. I would vote for the ap 2 option, make them take a melta cannon if they want to kill tanks.
My personnel suggestion would be to both disallow reavers AND redefine the D weapons. There are countless wacky forgeworld things to chose from. Right now "forgeworld allowed" really transates to "Angron and Strength D allowed". I want to see lightnings and trygons again next year, not just a sea of cobras and titans.
Another point, you need to change the fact that flier bases block movement. Using thunderbolts to stop people charging the Titans was just silly. Its the gladiator so more power to the flylords for thinking of it, but its not good for the event. Are my men really so scared of the plane's shadow they can't walk under it?
Also, I loved the scenarios this year, but I would suggest having a curveball of some type for assault armies next year. The vortex grenade was genius, keep it up.
And a million thanks to you and greg for running this event.
*PS* Oh, and whats the word on the fact that many reavers did not have their hull mounted weapons correctly represented? I pointed it out to my first round opponent, he said he didn't have to make it wisywig since there was not a official bit made for it. I knew this was incorrect, but I didn't want to start adepticon by raising hell about something like that.
Still, it looks bad when a non-wisywig model wins the gladiator. (correct me if I'm wrong, but I believe this happened) Were there any repercussions for this, or is wisywig now a polite suggestion rather than an actual requirement?