*sigh* I knew Peter David had made some changes to the Negima! English adaptation, to include adding at least one sexual innuendo joke. However, even people whom I heard complain about Del Rey's early adaptation never mention the extent of the domestication in the early volume (I know some more recent volumes from Del Rey are pretty good from what I can tell). But just to give you a sample, here's the Del Rey page on the left and a pretty accurate translated page on the right.
So, why is this important? Well, Konoka mentioning that Asuna is fast is the first clue given to say that there's more to Asuna than meets the eye (If you are reading the current chapters from Japan, boy is there ever more to her than meets the eye!). In another place (that I didn't scan), the Del Rey version has Negi imply that his grades weren't very good. However, you'll note that Del Rey has corrected this in later volumes by actually mentioning that Negi had good grades in school.
Basically, it looks like Peter David took every opportunity he could to add sexual innuendo jokes that weren't in the original Japanese. Then, he decided to add other jokes not in the original Japanese. However, Konoka making a joke about something else Asuna could do is dropped in favor of a re-write. I hate re-writes.
I'm told Del Rey fixed the egregious "Southern Master" errors in volumes 2-4, changing that to the proper "Thousand Master." I don't believe they've ever done anything to fix volume 1, and I for one think they should.
Don't get me wrong, I think Del Rey is the best of the manga publishers out there. However, volume 1 of Negima! is just awful despite the good usage of Japanese honorifics.
See also: Del Rey is Slipping.