It still seems that the only downside to a hydro / pto driven winch is the fact that they don't work when the engine is off. The only three times it would be off, in my mind, is in a rollover, if you drown the engine or if you have some other type of engine failure ( coil, piston failure, etc. ).
Scenario 1, rollover: you roll your truck, it's banged up and you're frazzled but hopefully not hurt. If I landed upside down the last thing I would think of is using my winch to pull me back upright. Aside from that, it would take some impressive rigging and a lot of nearby trees to be able to get a front mounted winch to pull you sideways. This is one of the reasons why you are only supposed to offroad with multiple trucks, so they can help you after the rollover, and then they can right your truck with their truck. Advantage mechanical winch.
Scenario 2, drowning: If you are mudding or doing a river crossing and you drown out your engine, your front bumper and therefore winch is underwater. The engine is not running and therefore your mechanical winch would not work. However, because your electric winch is submerged, I'm not sure that would function either, or even if you could reach it. I know you can buy sealed electric winches and solenoid boxes but I am pretty sure they're not designed to run underwater. Yet another case where the best option is to have a second rig strap you out of the water. If your engine was running, even with the mechanical winch was under water, it would still function as long as you could reach it. My pitch is that if your engine stalls out during a water crossing / mud bog, then you probably have bigger issues than whether or not your winch works. Advantage: mechanical winch.
Scenario 3, engine failure: Let's say you're tooling around and your coil / igniter dies. You don't have a spare. While you could use an electric winch to get yourself out of whatever trail you happen to be on, you won't be doing it fast but you could do it. However, in this situation I would rather strap up to my wheeling buddy and have him pull me out to somewhere I can work on it. Advantage: electric winch.
I think I'm going to stick with mechanical winches, but to each his own. That's my 2 cents.