Some very well thought out replies.
Anyone interested might look at the upcoming helicopter sim from Eagle Dynamics - DCS Blackshark. Release date is expected some time this year.
http://www.digitalcombatsimulator.com/
The developers have some nice video of the navigation systems.
Some reviews of the beta version here
http://www.simhq.com/forum/ubbthreads.php
Judging from available information, this promises to take PC sims to another level of fidelity / realism (considering of course the caveats made in earlier posts!).
Note: NFI and no first-hand experience here.
Cheers!