The 744 can do RNP and P-RNAV. The only thing it MAY not be able to do is RNP 0.3 approaches.
The -8 FMC works fine for most things. VNAV is a bit flaky on the descent, and there are problems with some approaches with tight turns (e.g., MEX). The "barely makes the grade" description overplays the minor problems. Second software update is supposed to be available this week to address most of them.
I have heard previously that the -8 FMS was going to be available for the 400; don't know the cost.
Last edited by Intruder; 16th February 2013 at 15:28.