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I think you summed it up pretty well: Speedlites are lighter and smaller.
You'll give up some power but gain some portability; you'll loose some large modifier capability but gain ETTL metering, camera-menu control (with version II Speedlites), and built-in (short range) remote control. (In case you didn't already know, the pop-up flash on your 7D can control up to three groups of Speedlites in Slave mode, if they're in moderately close line of sight.)
If you'll be shooting mostly in a studio setting, I'd keep the ABs; but if you'll be shooting mostly on locations, I'd go for the Speedlites.
Before you buy any gear, though, you might want to read this: