The FT-1DR is not friendly for GPS use. I sold it quick. The same with the FT-2DR after testing as well. If GPS is important to you and you want to stay with the Yaesu C4FM Fusion abilities, I recommend you find a used FT-1XDR. The GPS in the XDR radio works almost as well as my Kenwood TH-D72A; quick acquisition after cold start. This means I can leave the GPS off to save battery juice until needed.
I left the FT-1DR outside with a clear view of the sky for minutes and it had issues with acquisition. After 10 to almost 15 minutes it would get something, but the number of satellites were few. With the FT-1XDR I can be near a window indoors and it will acquisition pretty quick, perhaps one minute.
Other than for GPS use, the FT-1DR is a good little HT. As you do not have another HT with a GPS to compare it to, you do not realize how terrible it is. It is not broken as much as it is rotten. Sell it.
Yaesu also has this GPS issue with the FT-400DR mobile radio. They soon released the FT-400XDR along with the FT-1XDR to address the issue. Again, the FT-400DR is a good radio if you do not require GPS. If used at a fixed position, say at home, it would be fine. You can just manually enter your coordinates.
Signed,
A happy FT-1XDR and FT-400XDR owner