I would just like to add one more thing for education; I guess 15hrs per week or less is considered as part time. If work is full time and education part time then no worriesThis is just my opinion, but I don't think it would be a problem. As long as you can document that you were working full time (i think CIC considers working more than 30hr/week as full time). you should be good to go.
Also is your MBA program evenings / part time? you can document that to clarify as well.. Though I don't really see the need.
good luck.
See education on this link
http://www.cic.gc.ca/english/resources/tools/perm/definitions.asp