Mr. Ledyard wrote:
"But the koryu are full systems with the details of practice written in stone so to speak for each generation to practice without variation from the previous generation."
This is USUALLY a true statement however, it should also be realized that even in some of the Koryu arts, in particular, Muso Jikiden Eishin-ryu Iaijutsu (MJERI), the Grandmasters of the art can, and often times do, change training methods and also may even add entirely new techniques. In some cases these can be quite drastic. Imagine the suprise people felt when the ryu made the change from wearing the swords with the edge down to edge up as we practice it today. That must have had a few people scratching their heads huh?
I can only offer my personal view here but after training in both (ASU) Aiki weapons and in MJERI, for me, the feeling is much different while practicing each. In Aiki-ken for example, for some reason I don't feel the desire to outright dispatch uke, even though uke is attacking, but rather to survive the experience while preventing uke from mounting another attack. ( this of course may include dispatching uke, depending on uke's intent and the situation ). ;-)
While practicing MJERI, I will give the attacker an oppurtunity to back off from the attack by first drawing the sword slowly from the saya (if the situation permits). If the attack continues, then without hesitation I will dispatch the attacker as quickly and cleanly as possible using proper technique. There are no "degrees" of ending these attacks in this particular ryu as there are in Aiki-ken. You do not "pin" your attacker as you might in Aiki-ken, or try to disarm them. You simply dispatch the attacker. Done, over with, move on.
Even though the feeling, movements and intent feels different, there are technical commonalities as well, after all, they both involve sword and good swordsmanship can trancend style in SOME areas such as proper grip, swing, distancing, timing etc....
For me, today, there is a distinct difference. Someone with many more years of practice in the koryu arts might see things differently, as I might also one day, but for now at least, at this point in my training, I don't associate the two other than they both involve, and require, good swordsmanship. They simply were not developed in the same era, and therefore, tend to serve different purposes.
Hope this helps and didn't put you to sleep.