I would really love the IFD440 based on the features but for my experience after installing a brand spankin new one and experiencing GPS failure...
After having GPS failure on the newly installed IFD440, I bought a brand new GA-35 antenna and a brand new pro made RG400 cable to test the GPS reception on the IFD440.
With the new cable the 430w performed as it did with the old GA-35. As can be seen in the pics, good signal even when moving the GA-35 all around aggressively.
With the new GA-35 and new cable the IFD440 was able to receive good signal so long as the GA-35 was stationary, upright, with nothing above it but sky. As soon as I started to rotate it about 30 degrees laterally, it immediately lost signal. This is the same behavior as I observed in flight. This occurred with nothing above the GA-35, away from structures in the same location, cable, etc as the 430w test described above.
When I emailed Avidyne they offered no guidance except stating the GA-35 must be mounted on top of the aircraft. They did not offer an answer as to why the IFD440 was so hot. They did not offer a reason for the other error I was getting, although I figured that out on my own and resolved that with a change in the setup. I advised Roland Galindo with Avidyne tech support that if the answer was cutting a hole in the top of the plane that I wanted to return the IFD440. Roland said on May 17, 10 days ago, that he would run it by his sales staff. I have not heard back from Roland or his sales staff.
I have removed the IFD440 from the plane. I love the features of the IFD440, but... Given the failure of a new unit right out of the box followed by an apparent apathy from Avidyne, I will not be reinstalling the IFD440.
430W with upright GA-35
430W after aggressive movement of GA-35
IFD440 with stationary GA-35 and clear view of sky
IFD440 immediately after GA-35 rolled approx 30 degrees and unobstructed view of sky