The 60D is a major upgrade in terms of sensor, viewfinder AF, video, FPS, LCD and physical controls. If you shoot kickboxing, you'll get more keepers with the all cross 9-point array and faster FPS. For action, the outer cross points are a major major upgrade over the single axis points on the T3. And once you get used to the extra dials and buttons, you'll never want to go back to menu diving. The larger size is more comfy in most hands. I've owned a 60D for 4 years and it's served me well. I never bonded with the fold out LCD feature but the LCD is clear and vivid.
The only 60D gotcha is the lack of a dedicated FEC button. However you can assign FEC to the SET button and invoke it at moment's notice, albeit the scale is only visible on the LCD and not in the VF.
60D refurbs are $575 on Canon's website so make sure your used deal is significantly better. Finally, the joy of having a new toy to play with trumps most practical considerations, so I say go for it!