I took it outside yesterday, after re-doing the MFA and settling on +10. It is very good, outside in the sunshine, even at f/1.8, and now at any distance. I have yet to test it with this setting indoors, but it is so inconsistent in CFL lighting that I hold no hope. More later.
Fluorescent lighting in general is a problem because the color of the light changes continuously during each 60Hz (or 50 in the UK) cycle. Moreover, CFL and industrial lamps cause the AF system to focus differently. I shoot quite often under industrial fluorescents, so I have to settle on a value which gives usable behavior there. It is maddening to see the focus point shift somewhat randomly during a shoot, whereas under daylight it's pretty consistent.