What would be the criteria for proper battle-testing?
Here it’s been suggested that tBTC needs at least 3 months on mainnet without incidents: Proposal: Add support for TBTC - #37 by ramaruro. Similar expectations (3 months on mainnet) were expressed by Maker governance in response to tBTC application in May. As I understand, tBTC reached this 3-month threshold.
At the moment, Maker seems to be on the way to tBTC integration - it is marked as “Planned”: Collateral Framework Official - Google Sheets
Most probably they will start with a low debt ceiling, to reduce the risk.