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The only difference between the self-guiding CCD camera and the OAG solution is that the camera has a built in OAG guide chip ( Usually the TC-211, the same as the original ST-4 guider.. large pixel size but quite sensitive)
The OAG, yes does take a little more work to focus, but no more than a guide scope... and when it's set up you can get as big if not bigger FOV to guide on, the choice of guide cameras (QHY5, DMK, Atik etc) and the flexibility of positioning the guide chip to suit the field. Some OAG allow you to pick off the guide star prior to the filters so there's no significant light loss to the guide star.
Even if you have solid guide rings and support, you still have focuser "droop" to contend with; at least the OAG gives you some hope...
My 2c.
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