Which geobox did you look at it? The model I have has a ton of stuff in the manual, let me post. I dont even know what it all means exactly.Having looked at the geobox manual, they call it 2x2 corner adjustment, which is the equivalent of a horizontal and vertical keystone.
I dont see why you need a warping box personally unless the projectors you are using have shocking variance between their lenses. I would have thought 2 projectors can be aligned over the top of each other using no keystone and just slight lens shift to a high level. Of course, whether they stay aligned over time is a completely different matter, but that can't be helped by a warp box either.
Generally if you're having to use warping and / or keystone adjustment you're "losing" - they're things you should nearly never need in a domestic setting. I'd probably level that at A-lenses needing corrections. too, though I see the Envy has added pincushion correction recently seemingly to a high standard, and I'm in danger of incurring the wrath of the A-lens crowd
Why did I get it? I read all 120 pages of the Ultimate 3D thread on avs, and for most the thread everyone was saying the same thing. It's digital manipulation of the image, which creates some artifacts and lowers resolution. You want to avoid it if you can, just use lens shift. In 3D, both eyes arent seeing the same thing anyway, so if your alignment is 1 pixel off, that's only bad for 2D, but in 3D with the glasses, your brain interprets where things are supposed to be, so it's no problem, and digital manipulation of the image would just make it look worse without helping.
But no one had actually tried it. With all my reading, I only found two people who tried it. One of them was the creator of the Omega 3D system, so quite knowledgeable. The other was an end user. All their comments they left about it were completely clearcut. They didn't know what they had been missing. Whatever small dip in resolution it caused, being able to align everything down to the exact pixel made a significant improvement. First there is the convenience of being able to align things more quickly, but second, the problem is no matter how long you are willing to work at it manually with lens shift, you will never get it 100% perfect, especially the corners. Which again, you don't need to, they still said it works well without it, but it does, they said, make a big improvement.
But like a lot of the A/V stuff I'm interested in, there is not a lot of info about it, there are not a lot of posts about it, and there are not a lot of current posters who I can ask about it (since 3D lost a lot of popularity since 2010 and most users from then left the forum). So a lot of it is stuff I sort of have to get my hands on and see for myself. Which from a $ perspective, is a very bad situation to be in, lol. But I bought a lot of stuff used so hopefully that will help "insure" my project if it ends up that I have to get rid of half of it. Unfortunately 3D stuff is so unpopular, a lot of that is hard to find used, and a lot of that is the stuff I most cannot find info about whether I should get it or not. But I think this, even with little information to go off, is pretty clear cut if you can budget it and you are doing passive 3D. It will make things a lot easier, and it will improve the quality too.