From what i have gleaned so far ,most of the newer offerings with the plug and play feature.
Some of the older Kato units can be among the most difficult installations for diesel.
Steam installatons range from difficult to send this one in to be done by a pro
Yahoo sigs have a group dedicated to N dcc with a wealth of information in thier files section on installations.Well worth investigating if you plan on doing many of your own decoder installs.
The atlas u25b is a plug and play
the atlas new SD9 is also P&P with a decoder board expected to be available in late feb of this year.
My Bachmann connie is going in to be done by a pro.Ive read enough about the installation that i am just not comfortable doing it.Loys to the rescue