I'm thinking I can replace it then go online with RSNetworx and update the device mismatch and adjust from there.
The "Resolve Device Mismatch" function changes the identity of the drive object in the RSNetworx project file, so that you can upload parameters from the drive.
But it does not automatically alter the Electronic Keying in the DeviceNet Scanner Module's scanlist. That's how the scanner knows that the drive is a 3 HP versus a 5 HP, because each power rating has a different Device Code number, which is part of the Electronic Keying.
Electronic Keying is a good thing; it helps ensure that the wrong motor doesn't get turned just because somebody flicked a rotary switch a couple millimeters too far.
The easy thing is just to disable Electronic Keying for that particular Scanlist Entry. The slightly harder thing is to remove the Scanlist entry, and enter a new one that is mapped to the same locations in the Scanner module memory.
Auto Device Replace is a different thing: it will try to Download all the parameters for the wrong size of drive. Don't try that. Instead, update the ADR data by uploading from the drive and then saving ADR data to the controller.
I don't like to use ADR for drives. It's too hard for people to remember when they've made changes to tune the drive up, and then they're surprised when the PLC downloads the old value next time it makes a connection. And drive parameters tend to fill up the Scanner memory.
Unless you have a situation where you have to swap out drives frequently and very quickly, don't use ADR on them.