For face to face transactions, Bitcoin is no more secure than cash. The same methods used to forcefully take cash or items from you in a deal gone bad can also be used to force a bitcoin transaction. Most families would release the coins if their loved one was being held at gunpoint. I will agree that carrying a smartphone is far less obvious than a duffel bag/backpack full of cash, but anyone that can force you to give up the cash can also force you to send an email. I am not saying that it would be simple or easy for them to do, just that once your personal security is overcome Bitcoin and cash are equally insecure.
I see your point, but I still have to argue that Bitcoin is more secure than cash for face to face transactions. Many crimes are crimes of opportunity, and if there is no opportunity, there won't be a crime. And even the dimmest thug is going to think twice before turning a simple robbery into a kidnapping. Yes, if they are determined, they can kidnap me and attempt to force my family to pay, but I can tell them no all the same. Ultimately it's my choice (or my family's choice). Whereas if I'm carrying a bag of cash and get bashed over the head with a tire iron, I no longer have that choice. Perhaps small differences in the end, but differences that are important to me.
Any prospective thieves doing a face to face Bitcoin transaction with you will know that they need to force you to complete it. Its not like a random mugging escalating to kidnapping. They'll come knowing and ready to take you alive and conscious. I agree that it would be much more difficult to do that than just shooting someone in the back of the head and taking a bag full of money. I find it curious that you might place a price on what your life might be worth. Is there really an amount of bitcoins that you would rather die for than give up in a kidnap situation? I can always make more money if I am alive. No amount of money can resurrect me.
As far as authorities go you are correct. Having tens or hundreds of thousands in cash is often as bad as having drugs or similar contraband. On the other hand, courts are ruling that searching/copying cell phones during traffic stops without a warrant is legal. To be honest I havent been paying attention to any mobile bitcoin payment solutions, so I dont know how resistant they might be to a tech inclined cop having temporary control over the phone and imaging it.
Interesting. I wonder how the officer is going to obtain my cell phone without a warrant when it's locked inside my glove box, inside my locked vehicle. No reason to make it easy for them to violate my rights.
Oh, and if you have an android phone, you should check out Spinner. It's an amazing app, and I carry no more Bitcoins on my phone than I would cash in my pocket.
Your phone is not as secure as you think it is. Cops lie and cheat when they want. "I smell pot" during a traffic stop/checkpoint is probable cause enough for a search, and its impossible to disprove that in court. Planting a dime bag during the search is exceptionally easy, and who is the jury going to believe? Granted they usually reserve such behavior for those they strongly believe are doing something wrong. Also, most people carry their cell phones with them at some point when they are on foot, so its possible to lose control like that.
I just glanced briefly at the Spinner thread. In the context of security if you lose control of your phone to a tech savvy advesary, not only will they know the identity of your Spinner wallet, but by tracing the block chain they can pull all your other transactions from other wallets that you used to fund the mobile one. I know that you are exceptionally anonymity concious, so be careful. That is a potentially huge security risk.
I'm never more than 50 feet away from a connected computer or laptop, so I have no need for an Android phone