Apparently ENS went with a currently-capable-of-ZK-chain for Namechain over optimistic was because they seem to be under the impression that "finality takes 7 days" for optimistic rollups, an unfortunately common misconception. If you run a full node (and ENS certainly would do at least that) and you believe the fraud proof system works, then finality happens the moment the state root is posted to the L1 (5-10 min) and you confirm it matches your local root. This is no worse than a ZK rollup.

The benefit of current ZK rollups over Optimistic is the shorter withdrawal window, and little else. The additional complexity they involve unfortunately brings with it a host of additional attack surface area. I believe all L2s will eventually be ZK-powered, but IMO the current generation of ZK chains are reyling mostly on security through obscurity.

A doodler and computerer. I like permissive/permissionless open source, smart contracts, p2p systems, room-scale VR, and NixOS.

shazow.net

Currently: WhatsABI

Ahhhh, yeah there could be something to that. Will need to dig more into the protocol.

In the case of ENS, I believe this is the correct view because the rollup needs to interop with L1 state.

Maschinen Krieger, scale models and the occasional Gundam. 

Ethereum Core Dev - Besu - PG4LYFE

I no longer work on this stuff, and the deployment of fraud proofs are pretty new on many of these chains (including Base). I'd guess though that any entity briding significant funds to the chain would be monitoring the state roots for anything fishy.  Since there's a 7 day window, there's a lot of time to react even if you don't formally invoke a challenge via the fraud proof mechanism.

i think about this a lot. whats the most visible way to see what is going on wrt to fraud proofs? how often do they happen? how effective are they, what are the consequences, etc....

who is out there contesting optimistic rollups?