Good points. There is a serious difference in "intensity" of training. Also, of all 400+ Kung Fu styles there are hardly any that are effective for combat. But, there are a few that are GREAT. For anyone looking for the effectiveness of some of the few Kung Fu styles look here:
http://www.pachitanglang.com/mastersu/matute.htm
If you want to know which styles can be effective, read through this article, it'll give a brief description.
http://crane.50megs.com/index6q.htm