I think the suggestion of a used 40D (or 50D) sounds smart - I had the 40D and "upgraded" to the 7D and while it has more features (some I need since I shoot sports, some are nice, but don't do anything to improve my results) - the 40D was better for Jpegs straight out of the camera (at least in my opinion) - the 7D (like your 60D) has 80% more pixels on the same size chip and I find it requires a lot more post processing to get images as sharp as I got with the 40D without any post processing at all in most cases......and the 40D is an extremely well built camera...a big improvement in size and feel for most men's hands. The current cost seems like a steal when I see them advertised here on POTN for about $400 in good shape with low shutter counts.
I've been shooting professionally for over 40 years - I didn't own a zoom lens until I got the kit 28-135 IS with the 40D....I now have that lens and one of the 70-200 zooms. The 70-200 zooms are in a class by themselves - I have the 2.8 IS, but need it for poorly lit indoor sports. From what I have read, the f4 (non IS) is not only a LOT lighter, but is sharper - which is hard to imagine of any zoom lens....it's the least expensive of any of the Canon "L" lenses and may be the best or as good as any zoom lens made by anyone on the planet....
. The 55-250 IS may have the IS and a bit more reach, but the optical quality and the build quality of the 70-200 is in a different class entirely. IS is nice, but not really necessary if shooting outdoors in good light and certainly not necessary at all if using a tripod.
As for having two of the same camera bodies, I don't see why that would be a factor one way or the other...either you like the 60D or you don't - I can't imagine what there is not to like about it...unless you really need the extra amount of weather sealing on the 7D - how often do you shoot in the rain or snow or sand-storms? - and the lenses will be as susceptible to the weather to the exact same degree whether mounted to a 1D or the least expensive Rebel you can find.
I think the design of the swivel screen is great (have it on an SX10 Powershot) and the "flash commander" is a super feature if you use it.
edit - forgot to mention - the 70-200 F4 is an ideal lens for portraits -