I was doing basically this with a different sync tool, but I had a couple issues with it:
- If I needed to toggle ad blocking I had to go toggle it on both pihole instances
- When troubleshooting an issue I had to check two log sources, or disable one and then reproduce the issue again
- Sync was one directional so I could only make configuration changes from the primary instance
I've been a very happy Pihole user for years and years and Pihole 6 is the best yet, but once you're dealing with multiple pihole instances, Nebula Sync and Unbound, then Technitium is actually simpler to manage since it does all that natively.