Would love to hear more about this.

I currently dual in Lotro, and am Loving it, never had so much fun (for those starting out, I have a dualboxing Kinship on landroval, would love to have you there).

as for three boxing, and system requirements, there are some issues I can see, Lotro Eats RAM for Breakfast, and I find that even if the system is powerful, that there are sections in the game that lag down.

my setup is this
Main Comp toon1
AMD X25200
2Gb DDR 4200
Nvidia 8600 X2 SLI
Gbit Eth to second computer

Second Comp toon2
AMD 3800
2Gb DDR 3700
Nvidia 7800GTOC (single)

I find that on my second computer (I have the graphic turned down) that I have no troulbes, but because I am always looking at the first toons screen, I have the graphics almost maxed. After running through a bunch of Tweaking with the system, and Lotro client, as well as rolling back the Nvidia drives (DX9) I finally got rid of most of the graphical anomilies, but still when I enter PvP or the old forest I lag out, as well as Bree (though bree is so huge that I think the lag is an equation of their server)

I use mutliBox Server/Client to transfer keys from primary comptuer to secondary, and I have since installed AutoHotKeys allowing me to map out some simple macros on the second toon for casting Spells and healing (she is a Minstrel)
I think that I would find three toons Too much, as the only real "Macro" that the game has is a /follow, and you would have to be Extremely creative with AutoHotKeys or another program in order to have the characters space out and attack correctly without being able to "SEE" their screens, and adjust them individually from time to time, specially because the /follow command breaks very easily though the use of target assist is very handy.

Let me know if you are interested in helping Vae Victus, the unofficial dual boxing Kinship on landroval, grow in size. Currently we have one dual boxer (me) and a bunch of my close friends, one of which is looking into getting a second computer to dual-box.