Hi Harry,
the large template guides allow me to use a lot of cutters with my plunge router that would otherwise require a collet extension if I was using the standard size template guides (1-3/16")... yes, it's the exact same reason that Tom has been pushing the 40mm guide
I just made a simple base plate to accept the large guide bushings using a 1-3/4" forstner bit for the counterbore and a 1-1/2" bit for the through hole. I'm pretty sure that I got the idea from an old forum post by Bobj3...it's real simple to make a baseplate that will allow any router to use the large bushings
Greg