I was too sleepy at the tail end of that marathon day yesterday when this debate heated up at the end with 4 against one sleepy one.
smooth et al, you forgot another key point. You argued the high difficulty would only cause the miners to win a block every day ~200 minutes instead 2 mins (assuming the more plausible 100X hashrate attack), but the miners will leave because they become unprofitable (as the block reward doesn't increase but the length of time they need to mine for the same reward increases by 100).
So the your mining hashrate actually drops to 0 also under the attack scenario.
Duh!
PWNED.
You need to accept the fact smooth just woke you up, fed you breakfast, got you dressed, put you in your little car seat, and
TOOK YOU TO SCHOOL.

PWNED. REKTD.