Yeah, I was looking earlier and saw that. In fact, I think it was your v1 that gave me the filler idea. Apparently, due to some BC update that changed filler behavior, they don't effectively work for the "maximum efficiency" layout for tree growth. As of yet, the only solution I've seen someone use was two builders (at 8 diamonds apiece, mind you, then 8 for the template drawing table, for a grand total of 24 diamonds) with the same template to set the dirt/saplings after the filler finishes emptying the area (which requires an obsidian pipe) . Here's the video, if you want to take a look at it: http://www.youtube.com/watch?v=WG1-hTSSBbU&feature=related It could probably be adapted fairly easily to use a quarry instead of a filler, but that would increase the cost of the system to 35 diamonds.
Ultimately, it just depends on how much you want to spend and how sophisticated you want to get. Xaiier's tree farm is cheaper, but is slightly more complicated. The other linked tree farm is more expensive, but for all intents and purposes, is simpler.
Hmm, that farm is quite interesting, as well as his newer version.
The only thing is I don't understand why the trees are so spread out. Birch require 5x5 but normals can grow right next to each other, so in my farm it deals with that & means more wood per m^2.
And what do you mean about this "maximum efficiency"?