6 months are a short time for getting your own level of S.D. to applicability by learning Aikido. For most people this is likely to take a few years.
Further, if your purpose is to learn S.D. you should make sure the teacher gives attention to this element in Aikido. Some teachers place their focus on the self-development part of issue to the point it looses the essence as an effective martial art. If your purpose is S.D. you should make sure the teacher you are going to has the same opinion. To check this, you should both talk with him and with senior students, and watch lessons. If the content of multiple lessons for advanced students does not include issues that are essential to S.D. such as punches and other strikes, and when asking about it, you do not get a satisfactory answer (we are currently focusing on grab situations because ...) then that teacher does not teach Aikido for S.D.
The above suggestion is true for any other target you think important when considering going a class. Identify the content that has to be there, observe lessons and look for it, then talk with teacher and students (senior and beginners) and check if the content exists in the spirit you are looking for.
Note, teacher and student often believe in the system they learn, and their answers might be biased. Therefore, you should ask about content rather then "Are you teaching for S.D.?" or "Is your teaching spiritual?". I suspect all will answer yes to both questions, but this does not give an indication of the measure of importance they place on those elements or the way it is taught.
Amir