Any thoughts? I want to store by BTC safely and securely offline. Anybody got any experience of using trezzor for that? Positives and negatives?
if you want store something for long-term (years), securely and offline, go with bunch of paper wallets generated and distribute them to multiple locations.
for those that put all their trust in paper wallets, i believe you are taking much more risk than you think you are.
paper wallets are not any more safe than any other wallet and have some worrying attack vectors. they require too much 'trust' on behalf of the non-technical user. you have to trust that the paper wallet generator was written by someone with good intentions, and that the code hasn't been compromised since they wrote it. and the average user isn't qualified to decide if thats the case. Also, you get what you pay for. if it was free you have no comeback - who do you complain to (or sue) if in the future someone steals your coins from a deliberately or accidentally weak bitcoin address?
imho, they're unsafe for the average person to use and are better if the person using them is extremely techie and has personally examined and understood the (open) source, compiled it themselves, and is using it on a computer not connected to the internet (ideally, ever)
for everyone else, i.e., most of us... you really cant be sure if you're running a good version or a hacked version of the paper wallet generator code. And if you got it from a publicly available web site like bitaddress.org or any other paper wallet generator how do you know its not been compromised or weakened after the author wrote it? you won't know if the seed generation was weakened so someone can brute-force the address at a later date ... you won't know if the web site you got the code from has been redirected via a dns or bgp hack to a rogue version of the code. you don't and won't know til far in the future if your bitcoins are protected til you find out they're not.
then there's your own computer. does it have malware on it, before you print out the paper wallet? perhaps even afterwards. even if the paper wallet you downloaded and printed out is good, if there's any spyware watching what you're doing on your computer - or if your printer is on a network, any other computer on your network could spy on your printouts... or even your printer could have malware in it.. many printers are internet connected these days... etc... basically, using paper wallets have lots of attack vectors and you need a LOT of trust to use them.
At least, with a commercially available wallet, either hardware or offline software, you've paid someone for the wallet so there is a person or company to kick and to know who made it and who takes responsibility for it. whether its Trezor, Ledger, Armory, MultiBit, Electrum (or perhaps ChooseCase, that is both hardware, and multi sig).. at least there is someone behind those products that has a commercial responsibility and you know who they are and their work is being scrutinised by all at large, and in the case of hardware wallets, there are very few attack vectors once you trust the people who made them and the scrutiny of the open source... and the protocol for using offline wallets seems likely to be safer than randomly punching up a web address (like bitaddress.org) and printing out a paper wallet that 'the internet' has given you. seems fraught with danger and has too many systemwide holes to be trusted.
paper wallets downloaded from the internet, and printed out on your own computer seem to be for very trusting people who are willing to take a big risk with their bitcoins.