What bothers me the most about the Live Arena, and even the other one too, is the horrible mismatching of player levels. You can spot people who paid cash to get their Champs gear pretty easily at times. Sometimes just by their Avatar, such as people who get special event Avatars the day the event started. F2P have to earn this stuff. It just makes no sense to me to pay cash to win battles.
For example, I'm at Player level 75, and I was paired with a player who was level 56, and my average level 60, maxed out, with an average power rating of 55k Champs were dead before they even had a turn.
I know once a Champ hits level 60, the only way to make them stronger is with high quality gear. But no matter what I do, I'm just not getting it. I could... But I can't see paying to win. It takes the fun out of it.
At L75, you are really just getting started in this game. It takes a LONG time to accrue high quality gear, but it will happen. Get the best forge materials you can from Doom Tower, and never skip running your silver keys. Do as much Sintranos as you possibly can. The gear from these two spots is better than anything you can get from Dungeons.