Re: how many back talk would you take?
Not everyone naturally responds well to criticism, no mater how constructive the comments are intended. If someone becomes defensive to corrections, politely tell them this is not a competition, you are only giving feedback. Feedback is an important tool for learning Aikido. Make sure you are really giving them helpful feedback not telling them they are wrong.
Coming from another martial art they may feel they have some conflicting knowledge. Let them know you are not replacing their style, but you want to add to what they know.
Don’t let them clash with you (even verbally) blend.