Popgun
It depends on your requirements. PS1.3 is a remarkable program which replicates the 44 systems with great fidelity. It has the capability to accept user programming input and there is a wealth of info, technical and otherwise, on the Aerowinx web-site.
However, there are areas of operation which are not 'as per' the real thing. These are not hugely significant for straightforward sector operations - you can fly worldwide routes in almost any airline config with appropriate power plant set-ups. The caveat really applies to such things as 'what-ifs' The indications/reactions to certain FMC/ technical inputs/events should not be taken as guaranteed parallels of what happens in the big beast itself.
Overall, however, it's a super set of software.