Ego lesson: Seems that the lesson would depend upon your use of ego. Should a karate practitioner and an aikidoka take each other on? If both know ukemi, trust each other, and are not ego-bound to triumph, why not? O-Sensei took on practitioners of many arts with his new "aikido." It is not the action, but the spirit in which it is engaged, that would determine whether it is an admirable learning experience or an ego conflict, IMHO.
And if you and your instructor chose to do this in a spirit of joy and curiosity, I (and probably lots of other beginning aikidoka) would love to witness it.