All your stories are quite scary... But I have never had any problems with CoinBase, to be honest. In fact I'm Tier III already.
What are your limits at Tier III and how did you get it? I'm T2, but that seems to be all that is listed as available to verify on my account (10 BTC instant, 50 BTC/day).
Pretty sure there isn't a Tier III. What you have is the highest Coinbase will go. 10 instant, 50 / day. Which once you get, being linked to bank account, is by far the best deal out there for Americans. Not sure why people don't like this company. Go through the process, its simple.