Is there a preferred method to replacing my aging ISY 99i pro with my new 994i pro?

This is how I did it:

 

1 - update the 99i to the latest firmware.

2 - verify 99i is working properly.

3 - backup the 99i.

4 - remove 99i from the local network, and clear the java cache.

5 - add 994i to the local network, but do not yet plug in the PLM.

6 - check the router status to find the DNS assigned IP Use that IP going forward.

7 - Use Option D from new firmware announcement regarding how to access Admin for the 994i.

8 - backup the 994i before doing anything else.

8 - download and install the latest 994i firmware (matching version of the 99i).

9 - backup the 994i with the latest firmware.

10 - power everything down and connect the PLM from the 99i.

11 - power up and restore the 99i backup from step 3 into the 994i.

12 - set the location and time.

13 - manage modules to force download of 99i modules, and email Universal Devices to request all modules are transferred to 994i. They need the UUID of both the old and new units.

14 - Update the 994i username/password, and verify NTP works.

15 - triple check router to make sure the MAC for the 994i is allowed on the network

16 - reboot and review your programs (some may have Not Specified) items within if not all modules have transferred.

17 - at this point the 994i should be working just like the 99i.

18 - do a general system checkout.

 

19 - enjoy your new 994i.

 

Hope that helps.