There is an article in the latest Flight International about the delays and cost overruns of the US Presidential VH71 programme. An alternative that has been proposed is an upgrade to the USP's current fleet along the lines of the Carson blades/glass cockpit project.
I won't spoil the surprise about the savings that can be made, see for yourself, but they are enormous. To be honest, I don't have the technical ability to know how to post a link, sorry.
Now, if it's good enough for the President of the USA ...........
CD