Actually:
Rodimus, Stock + Xionia and Aphrodite (except Pure) all have Xionia kernels and should work on all phones. These are the very first OV roms, we used Xionia kernels from the Optimus S because we didn't have the ability to make our own at the time. While these should be usable on all phones and have the activation app, I highly advise against it simply due to age. By the time you get the apps updated, you will have little room left.
Bumblebee has a custom kernel that only works on old. Most others use stock or similar kernels, and also only work on old.
Harmonia and Harmonious Bumblebee use a custom kernel that includes support for new screens as well as old. Both are quite up to date and include the activation app and all stock programing codes.
Oh, and don't bother trying the activate app on GB roms, it triggers a hidden menu, which those roms don't have.
As for using the app, I have had to a few times due to experiments with OS roms, apps and kernels, but also, if your data speeds have been bad for a while, sometimes it will give them a jump start. That only works for Froyo, GB roms don't usually have this issue. Older Android was known to lose provisioning.