Rear disk brakes -- worth it or not?

[kipps]

My truck is a 3/4 ton 4wd, and will be seeing general farm duty, commuter driving, and some heavy towing.

I need to swap the axle under the thing, and there's two routes I could go.

#1, use a 1975 14-bolt full-floater axle that's sitting around already. This will need new bearings, seals, and brakes for $350. This axle is equipped with 13" drums.

#2, purchase a 2001 14-bolt full-floater axle from the junkyard for $285. This comes with factory disk brakes and a G80 posi-lock. Here too, I'd plan on spending around $300 for new bearings and brakes. The spring pads will need to be moved, but that looks doable enough.

Either axle looks like a good deal. I like the idea of disk brakes, because of weight savings and mechanical simplicity. My main concern is that I don't take a step backward in braking performance by switching to disks. I've had quite a few people tell me I would be downgrading, and their credentials indicate they should know.

Can anyone weigh in on this?