coinbase.com seems to take about 5 business days to complete a BTC purchase and I've read that this can cause them to back out if the price changes too much. Apparently they also give you the option to back out. Does this sort of thing also happen when selling? Is there a long delay with the option for either party to back out at completion?
No, selling is super easy on Coinbase. You sell at that price and they immediately start the ACH transfer to your account and you get the cash 2-3 days later. You see, Coinbase is slightly flawed because they DO NOT let you keep a USD balance on their site. So you can SELL immediately because that's your BTC balance but if you want to BUY the delay comes into play because they debit your fiat account first and then release the BTC to you. These issues would all go away if they allowed users to carry a USD balance on their site.
