I've got an XD9000 on my LR3 with a Devon D44 discrete winch mount. A little bigger can't necessarily hurt, but you can also ask yourself, how often and in what conditions do you anticipate winching in.
I'm not here to disparage warns mounting system for the LR3/4 (if they have one) or anyone other system. If you want a discreet winch, it is a good choice. I never felt like winch trays were all that strong, at least compared to the Devon.
The Devon completely replaces the inner bumper (tin) and has an integrated tray. It is very very tough, and very very solid. It also has some pretty hefty loops built in. If I were doing it again, and chose to go discrete I really like the option.
I'll provide you a link here to my gallery with a few photos if it is useful, you can PM me if you want for more details. The Devon is available with board sponsor
http://www.lucky8llc.com Justin @ lucky8llc.com and he's a pleasure to work with.
As far as the concept of using synthetic line to save weight, seems like a joke to me, when you consider the weight of a winch, bumper, mounting system, etc. I do have Synthetic line fitted, but I did not fit it to save weight. I saved weight by not adding an ARB bumper. I finally ended up fitting 80' of synthetic line and a decent safety hook from board sponsors
http://www.masterpull.com/ and an additional 50' extension. You can also use a snatch block, which can reduce the workload, etc, etc.
I understand everyone has an opinion, and a personal like or dislike. I am providing this information just to try and help show another option.
Gallery;
http://www.disco3.co.uk/gallery/thumbnails.php?album=21898
PM Me for info LR3/4 RRS Differentials, transfer cases, transmissions.