Dave,
This is surprising. (Given your penchant for destructive testing.) I was there when Byron broke a CS Bushman by nothing more than throwing it at plywood. (For the record, Byron is one of the two most dangerous people I've observed with a thrown bladed object, the other being uber-dan in the Bujinkan Bud Malstrom.) I was also present when my (now ex)wife bent a CS assegai badly by throwing it at plywood. (In fairness, it was a bad throw.) I'm not saying anything especially NEGATIVE about the Bushman, but both Byron and I were surprised it broke so easily. I did take a 4' dowel, and taper one end. I gave this and a Bushman to Bud, who was going on safari in Africa as an observer. That way, even though he couldn't be armed, he could have a belt knife and a short staff. My idea was to drill through the shaft, in line with the hole, and then put a pin through it. In case of deadly threat, that belt knife and useful walking stick would become a short spear.
Surprisingly, I don't find a 7' spear hard to maneuver in the house, and working in a confined space (hallway, etc) is actually easier, since it's harder for your quarry- er, adversary to evade. You just stick and flick, stick and flick. One good stick, though, and it's over.
Dale Seago is a ranking Buj dan, and prominent on Sword Forums. Yes, there are other ways to use a spear, other than just jabbing, but they're a little more advanced. I was told by someone who should know- who has over 30 years MA experience- that a 7' spear is best if you're a very good martial artist, but otherwise, a 9' is best.
I don't know how good I'd claim to be, but a 7' spear feels pretty good. 9' is extremely powerful- the typical training spears we were using were about 1 1/4" Purple Heart- but harder to maneuver in other than a back and forth motion. If one did use a circular strike, though, it was like Thor's Hammer hitting.
John
