I know that there are several brands of hardware wallets with open source firmware that are considered safe. Is it better to just one that is safe and you are most familiar with? Or would hedging by storing coins in multiple wallets make sense just in case some exploit is found in the future?
Personal, I would use multiple wallets just in case some exploit is found in the future. For the more paranoid/safety conscious person, I would also place the hardware wallet in a mini faraday cage, until needed. The reason behind the faraday cage is that electromagnetic radiation of WIRED or even hardwired devices can be picked up from up to 65 feet away; you could turn off the device to combat that possible risk (instead of a mini faraday cage)... Don't take my word for it... here is a short youtube clip of this in action. I would also use only a external hardware wallet which only connects to the internet by Ethernet cable for the same reasons described above. When not in use, simply disconnect it from the internet... this further improves the security of the store private key.