From a couple of papers I’ve read, it’s best to connect a surge protector to neutral, not ground. It prevents high voltages from appearing on the chassis of connected devices (basically anything with a ground prong). Plus, the neutral is a lot fatter conductor than ground.
No downside. I do want to point out that even whole house surge makers recommend you supplement with protectors at delicate devices due to a couple of issues:
- Clamping voltage of whole house protectors is usually pretty high, 600 to 800V. I have a WH protector and the one device I lost during a lightning strike was a laptop plugged in directly overnight. It was an old laptop, but still, I could have gotten more use out of it.
- The distance between the panel and device may be long enough that an induced surge via electromagnetic coupling to a lightning strike can’t be protected by the panel alone.
Lastly, the 2020 NEC requires whole house surge protectors so you’ll be moving your panel towards the latest standards. Highly recommended.