I don't know if this addresses all of the issues here, I won't read through the billion or so posts in this thread...
...but one potential issue with training can be dealing with non-Aikido style attacks (punches that aren't like sword-thrusts, wrestling tackles), and of course, the principles for defense are still the same, but saying that and actually training with nontraditional attacks are two different things. Anyway, what I really meant to say when I started this post- I just took a class today where my sensei went over dealing with boxing style jabs, tackles, trips, in general mixing it up, and it was not only a lot of fun, but it felt like good training. My point- good to mix the more traditional training with training in how to deal with other styles of attack. And may this thread run forever! All hail the invincible thread!
