I hear you.
But how is a Droid-branded phone any different from a different Android phone? They run the same OS. If her Droid is "flaky," then either there's an actual hardware issue (in which case a new phone of any kind would fix it), or there's a problem with the Android OS (in which case, no other Android phone would be any different), or it's user error (in which case, nothing can really be done about it). That's why some suggested doing a complete wipe and reset of the phone. Unless you're messing with roms and stuff on a regular basis, or downloading bad apps, I don't think there's any reason it should get progressively slower with time.
Droids are no different from other Android phones; they're not even all made by the same company. Some are Motorola, some are HTC. It's just a brand name Verizon uses.