Upward or Lateral Move? And should I wait until after MBA?

I currently work in client service for a BB PWM team in a centralized location and never go to the market office and meet clients. However, I do speak on the phone with clients. I have an interview with another BB PWM team for and investor assistant position. This is located in the front office in a major US city. I am also half-way through a two year part time MBA program. Do you folks think this would be a lateral or upward move? Additionally am I better off waiting until my MBA is done and apply to associate programs or could the assistant position lead to an investor associate position? I don't want to hinder my career because I couldn't wait one more year.