But things aren't all that rosy when it comes to 3D. The roughly 50% brightness advantage for the Panasonic makes a huge difference. The HD8300 was one of those that I find to be somewhat dim. That's correctable with high gain or small screens, but, it's a significant downside to those really interested in 3D and reasonable brightness. Fine for those who don't find it as dim as some of my friends do. Let me put it this way, on my 100" size for 16:9, I think the Panasonic gets the job done. (I don't want a screen high gain enough to matter and significantly narrow the viewing cone or corner brightness). The Optoma though, is a bit rough with some of its dynamic controls, not the best CFI, or iris action.
To summarize, the HD8300 will appeal more to the purist, for the rich colors, and image depth, slightly better blacks, wanting the best possible picture quality in 2D. The HD8300 can deliver on that, and a longer warranty as well. The price difference of $1000 or so will be a big determining factor, but one of these two likely will have a lot more appeal to you than the other, even forgetting price, and that should make choosing somewhat easy.