Here are my suggestions
1) Add a lobby filter system that is attached to your user profile. I would like to have my filters be saved for each time I log in. A LOT of users clean their browser daily using an application like ccleaner or the like. My system has some edits to automatically clear browser data upon closing my browser. I would like to see the filters be attached to your user profile so that they stick with you
2) TF2Center wide lobby system- I don't know what to call this but here is the explanation.
TF2Center should have a system so that it remembers my current lobby that I am in currently. So that when it is time to ready up and I am on different parts of the site I don't have to open a new tab to keep the lobby page open. It should have a popup of when your lobby is readying up so you do not loose your slot. There should be a button you can click that would take you back your lobby page from different parts of the site.