Uffe wrote:
Many patrol owners said "don't do it" because the skids collect dirt and will rust your car more easily. Another guy says it is a liability because if vegetation is caught on the skid it is prone to start a fire
Those sound like people who do not take their trucks off road but are offering advice on off-roading.
Skids may rust, as will every other part of a car or truck (particularly in a place that uses road salt). But they don't mount to the body of the car. Where they come in contact with frame rails, the mounting is tight and it would be impossible for dirt to get in there. They may accumulate some dirt and mud on the top side of them, but then again, so will your transmission, axles, fuel tank, muffler, etc... No more or less of a rust risk than any of that stuff.
The only part of your vehicle's underbelly that should be getting hot enough to be a fire risk is the exhaust. If anything, a big skid plate would reduce the fire risk by keeping vegetation from coming into contact with those areas to begin with.
On the other hand, running a relatively low clearance rig like our Liberties over a rocky, rutted road has a very high risk of cracking an oil pan. In the case of the Liberty CRD, your oil filter dangles down completely unprotected, and is one of the lowest parts of the vehicle. Not running at least the MOPAR engine, transmission, and transfer skids is a really, really bad idea if your Jeep ever goes off road. I only use my Jeep to access hunting and fishing spots, and my skids are already scuffed up with all manner of rock and dirt rash. I shudder to think of how many times I'd have knocked my oil filter off 50 miles from the nearest mechanic.
Over the last 20 years, I've had skids on my old 80's Toyota 4wd truck, a Nissan Pathfinder, a Toyota Tacoma, a Toyota 4Runner, and now the Jeep CRD. Some of those vehicles have seen substantial off-road use. Never experienced a fire (or even smoke) with any of them. The 1985 Toyota pick up has had skids on it since day one, and last time I checked, there was no evidence they were rusting out (this despite them carrying many softball-sized dents from impacts over the years).