While the 609 is a very cool plane for civilian use. It will require fairly extensive cockpit modification for it to be used as a viable military/rescue asset. First of all the 609 has a collective much like a helicopter. While this may get rid of the collective dyslexia that some pilots face during transition from helos to tilt-rotor, it doesn't have the same TCL functionality that the V-22 has. Even if the collective stays you will need to add a altitude reference feature tied into a Flight Director Panel controlled by the mission computers and the FCCs. All of that is required to take advantage of the hover coupler features and position hold features that the V-22 has. The basic 609 doesn't have this functionality included as it isn't a requirement for a civilian operator to hold precision hovers in a low visibility environment.
The 609 is also lacking the full control of the nacelles that the V-22 has. The V-22 has a thumbwheel that the pilot can use to position the nacelles from 1-96 degrees with an additional 1.5 degrees supplied by disc tilt. The 609 is designed with fixed nacelle positions in mind. It isn't meant to have prolonged operations at various nacelle angles from 1 to 96. Basically it has a hover mode and an airplane mode. I haven't heard if there is a conversion mode setting.
For rescue work the airframe is going to need to be stressed for hoist operations and include various upgrades in communications, flight instruments, and probably a color weather radar. The plane should also include a larger fuel capacity as well as the current fuel limitations with the 609 wont give it much more of a range advantage over the HH
Do I think any of these options are insurmountable? No, but the development costs will be fairly high I think and by the time the Bell is done nickel and diming the USCG (if they were to pursue the aircraft) they might as well as taken a CV
-22 with the defensive systems removed.
Edited for grammer errors.
[Edited 2007-03-28 05:18:48]