I'm going to echo pretty much the same thing as everybody else here is saying. If your only concern is offroad performance in 4wd, then a spooled or welded front WOULD work, and be cheap... but it's not really an ideal solution. Your turning radius is going to suck, you're going to be putting a ton of stress on your steering components, and forget turning at all in sloppy/wet situations where you don't have a lot of traction (snow, mud, etc). It's just going to push you in the direction your rig is pointed.
If you're driving it on the street and have hubs, then it will work, but only if the hubs are unlocked. I know around here some people leave their hubs locked in in all winter (if they're open in front), just because you never know when you might need 4wd. If you're one of those people, forget it, because it will be dangerous and probably close to undriveable in icy/snowy conditions with the hubs locked in in 2wd OR 4wd.
Of course, the rear is a whole different story. I love my welded D44, it was cheap and easy, and I drive it every day on the street. A little extra tire pressure in the rear helps the tires scuff a little better around tight corners instead of stressing your leafs/bushings/shackles in the rear. Tire wear is increased a bit, but it's not too bad, and I'm even running Super Swamper Radials, which are not known for their long tread life.
I have yet to see how my rear end is going to work in the snow. I imagine it will take some getting used to. I take it easy in the snow anyway, so it shouldn't be too bad. My brother's comanche with a detroit in the rear, however, is going to be a doozy in the snow... no weight, and the detroit likes to make the whole rig lurch to one side when it unlocks in a corner when you let off the gas. At least my welded diff will be predictable.