From what I know, the 6500K lamp does use an M59 ballast. I had thought that the 4000K lamp was a pulse-strike, and needed a different ballast.
As far as my anime collection, well, it's quite large. I've been meaning to come up with a complete list of it, but haven't found the time. I have a lot of DVDs in general. Tons of anime as well. Stuff I'm currently watching tends to get put on the hard disk, so I don't have to look for disks when I go to pick up the next episode of whatever. It seems though that when I get to the end of a series, I tend to just buy more hard drive space instead of deleting what's there, so there's about a terrabyte worth of stuff on the drive, probably 2/3 of which is anime. Actually most of the other 1/3 is high-def stuff.

While I do like the 6500K lamp, I don't know that it's all that huge a difference in viewing experience. The 4000K lamp looked great to me before. Your eyes adjust to the slightly warmer white balance quickly. Actually, it's probably better if you are adapting from incandescent lighting.
So, as far as I'm concerned, now I just have an extra lamp.