I have two issues with the long spear:
1) It can overhead through teammates. Everyone knows it's a problem. There's nothing that can be done about it, theoretically, until the WSE comes out. I think the overhead should simply be removed until that happens, and then, if possible, both the pike and the long spear should be given 'high' thrusts.
2) Everyone and their mother can carry one into battle. I think the slots taken should be raised to 3. Right now, it's too easy to hybrid a regular melee build with a support build, simply by bringing a long spear to fill those extra equipment slots.
Coincidentally, I can see two questions coming up right off the bat:
1) Why would anyone use the long spear over the pike?
You can use one with a 12 strength build, and the other you can use with an 15 strength build. Hopefully the long spear would have a price reduction as well.
2) Won't everyone who carries a long spear + 2 slots of gear simply switch to the bamboo spear?
Maybe. And that's perfectly fine. The bamboo spear has a manageable 200 length, forcing the user into combat range. It also has slightly lower overhead damage than the long spear, so it (presumably) would glance more. It does only require 10 strength, so current dedicated long spear fans and newly-retired peasants would be able to use the bamboo spear in a similar way the long spear is used now. The only difference is the higher chance of personal risk.
Just my two cents. Since everything else can spinstab, I don't really see the point of arguing about it in this one specific instance. I'm not saying my solutions are necessarily balanced, together or separately, but I think they're the best fixes for the problems I listed.