The appliance vendors mentioned enjoy the speed of having selected hardware and designed ASIC's to specialize in their product's tasks. This can be a double edged sword though: a show stopper bug in the firmware is likely probably going to opaque to anybody but their engineers. Additionally, if a component needs replacement, there is little possibility of finding a replacement amongst your existing hardware inventory.

Vendors that implement their product in software at least may provide some relief with respect to troubleshooting. f5 Network's Big/IP runs on suped up PC's running BSDi, so besides the tools that f5 provides for monitoring Big/IP one has the full suite of BSD tools for minding the health and well being of the systems. HydraWEB and Coyote Point also appear to be providing routers on PC's. The former refers to their basis as HydraOS, one shouldn't be surprised to find Unix under the hood (OK, I would be surprised to find NT!). Coyote Point's Equalizer runs on BSD, they don't state which one, I'd hope it's FreeBSD.

The hardware vendors of course reckon that there won't be the failures one sees with PC's. There are no disk drives to fail; the only moving parts are fans. One has to weigh all these claims on their merits.