We couldn't possibly answer this question as there are multiple factors to consider, and at the end of the day its you that has to be comfortable with keeping a large amount of Bitcoin in your own home. I wouldn't even keep my life savings in one place let alone in one wallet, but then you have to consider if putting it in multiple locations is any safer. An option you have is splitting the passphrase up into multiple pieces, and storing them in multiple locations. Thus rendering each bit useless without the other. However, that might be going a little bit overboard if you're comfortable enough with the setup.

Some of the things to consider, and ask yourself:

- Likelihood of your house being burgled
- Likelihood of where your coins are stored from damage (flooding etc)
- Whether anyone knows you own Bitcoin
- If your house was burgled, how easy is it to access where the wallet is stored
- Considering the fact that your house has documents, and pictures the thief might be able to identify you, and your family members, and potentially guess that.

Probably more that I'm failing to remember to as of right now. However, despite all of this your setup is likely more secure than the majority of users on here. Although, all of this is subjective some users here will pick a bone with sharing with family members in case of death or they might be worried that the USB you intend on using might be compromised, but its all down to your personal comfort level, and trust.

Are there security issues with your proposed setup? Yeah, definitely. However, its a better setup than average.