Skyking
The midcont interface is the only one that is APPROVED for the 90b and the 525. The issues are RAIM, arming and annunciator light status provided by the 90B and more important FAA approval.
I agree with kevin(mcdo) that the 90B is not as intuitive as the garmin, however, it is not lacking in database, approaces, or reliability. I sure like the altitude alert function. i use that all the time.
Another trick is anytime i am doing an approach or even a visual I set the GPS to OBS mode and the 525 command bars steer me to the runway and the distance shows to the MAP. Great for low viz days. Works like kns80 RNAV with no restrictions.
I honestly do not think a bw map is of much value after using the 295 or equiv. I think the installation is a lot of work when you can hang a map from the control colomn and use it for a backup for 1k$.
I could live with the 90B without anything else, however, going back to VOR navagation would be for the pits! Best investment was certifying the 90B for approachs and enroute.
http://www.mcico.com/MD41-300.pdf is the manual. The switching is different for the 89/94 and the 90B. You CANNOT HAVE BOTH.
fyi
bob