I too have a Yaesu FT1-XD and use it for spotting when there is no phone or Internet signal. While it has been a lifesaver for spotting, I must agree with Joe, OE5JFE, that it works but is not fun to create messages with the keypad and thumbwheel.
I just wanted to add that if you create a test message at home and send it (even if it doesn’t reach an igate), it is much easier to edit that message on the summit than it is to create a new one. If your test message is complete, all you should have to edit on the summit is the frequency. Doing it this way saves a little time.
Hope that helps. 
Ron, KI4TN