So in a way LiteON is trying to tell you that the big if not only difference in 812 is the 8x -R writing speed and the use of sony technology, hence better quality.
In other words it would not be logical for them to update the 811 to allow it to perform like a 812 now would it.
Also the 411 drive is being phased out and no longer in production. Whatever 411s you find on the market are the current stock, once it runs out it's finished.
As to the improving its quality, there is no plan to improve writing quality on the 811 through the firmware. If they do intend on releasing new firmwares it will be for added media support, but the current quality of the drive will remain the same.