A few months back I was in a position to do some mods to my Defender to improve its performance, I chose a manual locker for various reasons. Since fitting it, I've had the opportunity to go out with a couple of vehicles with a fair amount more travel than my standard suspension setup. After seeing both in action, not once have I regretted choosing the locker over suspension mods and should the need ever arise, I would choose the locker again. Outside of tyres, it's probably the best single mod you can do to improve a vehicles off road capability IMO.