I mainly applied to carry when I travel in the future. Thinking about moving mainland in the next couple of years. I did use a money order (western union) for the $60 fee. Hopefully everything goes smooth
If you're exclusively carrying non-resident CCW permits from various states (as Hawaii residents have been forced to do), it's advisable to have permits from a few states.
The agreements and rules for reciprocity tend to change. One agreement can expire, leaving a "gap" between the expiration date and whenever they get around to renewing the agreement. For example, if Ohio honors Florida's permits, for both FL residents and non-residents, but the agreement was for a 5 year period, that period might end while you're traveling to Ohio. You might not be aware the agreement hasn't been renewed, so technically you are carrying without a permit.
You might also be traveling with a non-resident CCW permit from FL, not knowing the Ohio law changed to not honor NR permits from FL. Again, the goal posts moved without you knowing. Perhaps FL enacted a new, less strict law for non-resident CCW permits that Ohio doesn't like, so they stopped honoring that state's NR permits.
There are many other ways to get caught during travel with a permit that was okay before but is now invalid where you are heading.
If Ohio also honors AZ, NV, UT or other "popular" states' NR permits, and you have one of those in addition to FL, you'd be covered if FL is suddenly rejected.
Overlap and redundancy can help keep you from breaking the law when traveling, Also, since not all permits are honored in the same states, a second permit might offer a few more states in which to carry that your first permit doesn't. Added bonus!
I look forward to national reciprocity, where non-resident permits are sold on eBay as collectibles.