The center hole in the drum needs to machined bigger to fit over the hubs, or do a disc brake conversion. The hubs are definitely the week link, I've broke 3-4 over the last 12 or so years I've been running mine. Warn still replaces them under warranty with a copy of the receipt. I switched to drive flanges a couple years ago, and last year I stripped out the splines out of one side my spool, so as far as strength I think the kit is pretty strong.
For reference I run a 351W bored .060 over with approximately 9:1 compression, C4, dual dana 20's, 4.88's, and 37 inch Krawlers and I drive it like I stole it.