Brandon,
Nice form.
Good point on the twirling. Twirling the bo is an excellent wrist flexibility/strengthening exercise, and therefore useful, even in kata.
There is a common two handed spin of the staff that can be found at the tail end of the excellent kobudo segment from the superb Japanese documentary - Budo.
http://www.youtube.com/watch?v=Yzc3lsacKNI&feature=PlayList&p=026FADA118C7A52E&playnext=1&playnext_from=PL&index=10There is a variation of this spin done in Chinese Gun Shu (stick/cudgel art). Check out the Gun Shu form below, especially the spin starting at :40. It is hard to tell in this video, but the speed revs up in each of the three spin sequences. I have been taught pieces of this form by a Chinese Tai Chi master, and I can assure you that by the third sequence, the Gun can be spun at enormous speed. It makes an wonderful whiffing sound.
http://www.youtube.com/watch?v=dolbFKl2zQ0Both videos above are basically two handed spins, though the gun movements have a small transition section in each sequence that one hand is only loosely holding the gun.
I believe these are a bit different from the one handed spins you did in your form.
In the spear forms I practice, I have some small sections of spinning attacks where I have the spear momentarily in one hand. I train against targets, which I will show in future videos, and once contact is made against a body, there are follow up movements (stabs).
This is how I distinguish between a two handed attack, and a one handed spinning attack, found in the following video at :11.
http://www.youtube.com/watch?v=G03MWz9v5jcThis attack could easily be a two handed only movement with the spear stopping at the extended position. That could be both a block, and also an attack where a block was anticipated. But in the case where a was highly confident that the attack could reach the target (say the person may be facing away from me fighting one of my fellow soldiers in battle), then the spin of the weapon increases the speed and force that the blade will hit the target.
That is just one of many scenarios where I have a reasonable confidence that I will hit the target and want to use the extra speed of the spin to strike the target. Kind of like swinging a baseball bat or tennis racket. You follow through on the swing, and don't stop halfway.
So short spins, where one hand releases only very briefly, can be used in some applications.
-Budoka Mike Eschenbrenner