[CentOS] Experience with Centos running off usb-stick(s)

Hi, I'm trying to build a redundant duo of firewalls/routers/gateways and I'm thinking about not putting any disks in them and instead using a usb-stick raid-1 as storage. Has anyone any experience with this? Since the machines will be running pretty much only iptables, conntrackd and keepalived there is not going to be a lot of disk activity going on and the plan is to do all the logging on a remote machine which should reduce the write activity on the sticks to almost zero during normal operation.

I've already created a fairly minimal kickstart for such an installation but I'm wondering if there are any opinions out there on whether this is a feasible approach or if there are any gotchas I'm not aware of.

Regards, Dennis