There are a lot of advantages with a newer body (60D) over an older body (5Dmk1). It doesn't really matter which newer body against which older body, the newer one will almost always win. You can compare pixel counts, ISO ranges, noise, focus, and support/waranties.... the new body almost always wins.
To me, this seems like a question of full frame over APS-C. The 1.6 times factor for APS-C is great for that extra reach for wildlife shots but can be terrible for wide angle views. Yes, you can use a 10-20mm lens on your 60D ( got it and love it!) but any superwide lens really distorts the view. A full frame sensor will give you less distortion on those wide shots.
Thinking outside the box..... remember that this is DIGITAL photography and not FILM photography. With digital photography you have the additional option of using a lens that is not wide enough to capture your subject (less distortion), taking multiple shots, and stitching the works together at home to create a more pleasing image. The 60D does not have a panorama setting, you have to select your frames manualy. Even if it did, you are better off processing at home than an auto feature built into your camera... sort of like shooting RAW or JPG.... one is more convenient but the other works WAY better.....