Yeah, spools are always locked. I think of them as that chinese finger pull trick. I think though, if you want to continue having your truck as a daily driver, a spool is a bad idea. Increased tire wear is annoying, and continued driving on the streets WILL result in axle snappage. Just because it hasn't happened to some of you doesn't mean it won't!
Granted bigger tires like 31's and 33's can cause this more so than smaller.
IMO for a daily driver, a lock rite is a better choice. You get used to the ratcheting noise, you get used to the popping, and extra torque steer, and if you have an auto, you don't notice too much that it's even there. The fact that a lock rite disengages around corners just means that much less tire wear, and axle ratcheting.
My experience with a spool on a daily driver with 31's was that it would ratchet the axles back and forth around corners. You could actually see the tension in the axle shaft as it rocked back and forth while the tires squealed around the corners. This has a tendancy to gradually weaken and then twist your splines.
Spool 5 Axles 0
I had one breakage with my lockrite in the time I had it in. Which was longer than I had the spool installed. The reason for the breakage however, was that I was situated between rocks, and I was trying to back up over them. One of my mudflaps caught between one of my tires and a rock, and as I torqued up going backwards because there was no slippage on the tire stuck on the flap, it snapped that axle.
Sorry to be so negative on spools, but that little $99 charge on a daily driver like mine ended up costing me 5 axles, and a set of tires. If your rig is going to be mostly on dirt, or on trails, and not a daily, go for it.