I have not verified the part values, but the schematic looks ok to me. I build a lab supply with the LT3083 once and it worked fine. Did you take the Vdrop into account? This might explain why you are only seeing the 800mA instead of 1A. Try a supply with a higher voltage and see if that helps.
In addition to that you could run a simulation in LTSpice to verify your part values. It's easy to use, free and quite accurate, especially for LT parts ;-)