I've used lovejoys in some older projects and then tried the oldham style with a disc... much more accurate in my opinion and simply a better design. I eventually started making my own on my cnc mill using round aluminum stock and delrin for the disc. A pretty simple project especially considering the cost of these couplers. You say alignment isn't an issue but the oldham type couplers are also much more forgiving overall regarding alignment without sacrificing accuracy and providing minimum backlash. The gantry weight shouldn't be an issue.