I can't speak for the FT-1DR. On the other hand, I have a Kenwood TH-D72A and a Yaesu VX-8GR, both APRS radios with built-in GPS receivers. I love the Kenwood; I hate the Yaesu.
Yaesu's user interface is lousy, in my opinion. Other than one set of menu items for normal radio operation (100 items) and another set for APRS and GPS operations (27 items), there is no organization to the menu items. As a result, I spend a lot of time scrolling through items trying to find the one I want. Also, menu items that require entering text as well as entering APRS messages requires the use of non-intuitive keys to move the cursor around. Finally, the Yaesu is useful only as an APRS tracker with messaging capability. There is no way to interface the radio's TNC with an external computer.
On the other hand, Kenwood grouped menu items in a logical, hierarchical arrangement, in my opinion. It's a lot easier to find things in the Kenwood menus than the Yaesu menus. The huge difference is the four way rocker switch on the Kenwood which you use to navigate the menus as well as move the cursor when entering text. Kenwood also allows external access to the TNC so that you can connect a computer running an APRS client program along with the internal TNC. You can also use the Kenwood to do regular packet radio.
Yes, the TH-D72A is more expensive. But, I think you are getting a much more capable and usable radio. I would have to take a serious look at the FT-1DR's user interface before I would consider it as an APRS radio.
Here's a link to a web page that compares APRS radios. Unfortunately, they do not yet list the FT-1DR.