If half or more of the hash rate is down for some reason, how long would it take to find blocks with such a slow adjusting difficulty?
This is not a hard question to think through.
Assume we lose 1/2 of all our hashing power - let's call this the "worst case scenario"
The average confirmation time would double from 10 minutes to 20 minutes.
The adjustment period would go from about 10-14 days to 20-28 days.
The network would adjust in about 20-28 days and we would be back to 10 minute confirmations.
Although a bit of a PITA for maybe a month this is certainly not anything I worry about and remember this is the worst case scenario.