Wall hauler is obsolete. Pro-Traxion is getting a nasty reputation for falling apart (letting the rope slip off the pulley) under high loads, or any funkiness in the orientation. Google up the zion accident a couple years back. Complicated set fo events, but essentially the rope came out of the pulley while someone was jugging the line, the system shock loaded, rope was severed by teh juggers ascenders and he died.
Block roll so far has a loyal following. Big pulley and ascender also works.
I thought that the conclusion about the Protraxion was that the reason that it was letting the rope slip through was because people weren't putting the carabiner through the lower hole; this would thus (to my understanding) prevent any rope slipping out. (please correct me if i'm wrong)
OP-is there a reason you want to get a different hauler? just curious cause I'll eventually want to get a good hauler as well.
I studied a protraxion in action during my last wall and concluded that the protraxion is safe as long as you give it enough freedom of motion for the pulley to align itself with the direction(s) of force. It's why you don't want to haul directly off a bolt (i.e. use a sling between the bolt and hauler) and why you don't want to set up your ratchet using the bottom hole.
Other systems have the same problem, but they don't explode. I ruined a very nice pulley, for example, by clipping directly into the bolt to haul.
The biner in the bottom is not the issue. It basically seems that once the hauler has been beat up a bit (as wall life tends to do) that the front swivel plate gets enough slop as to be able to accidentally not engage the pulley (it slides on top of the grooved slot by the button instead). If this happens and is not caught, the rope can torque off the pulley under load. There have been several reports of this happening. The biner prevents the rope from completely coming out of the device, but you better hope it's through you (i.e. ascender or gri-gri you are using to haul) or as in the case of the accident it will let all your slack out and possibly strip you and your anchor from the wall.
Additionally as mentioned, you do have to give the thing freedom to pivot around as you haul, or the rope can come off the pulley and wedge between the front plate and the pulley. The biner in the bottom prevents the rope from coming completely loose, but you're still in a world of hurt to fix it.
Play with a pro-traxion with a biner in the lower hole and see just how much you can still open the device with it in place. It doesn't do much.
It is not a bad device, but it should not be used for very large loads, should be watched very carefully. I have stopped using mine and went to a big pulley plus ascender combo.
I've never used one but I'd get the block roll in a second to replace the protraxion if I had the cash laying around. So far I've had no problems with the protraxion, and have no quarrels using it to haul (I've never hauled more than ~70 lbs though). As long as you use a transient biner and a little forethought you shouldn't have to worry about weird angles loading the pulley.
However, think about what the protraxion is: your locking mechanism is a toothed mechanism that clamps the rope against a pulley that is made to slide....
The block roll uses something like a basic to hold the rope. I'd trust that a hell of a lot more than the complexities of a protraxion.
This is just something I've thought about, I've never used one but I know people who swear by them.
The biner in the bottom is not the issue. It basically seems that once the hauler has been beat up a bit (as wall life tends to do) that the front swivel plate gets enough slop as to be able to accidentally not engage the pulley (it slides on top of the grooved slot by the button instead). If this happens and is not caught, the rope can torque off the pulley under load. There have been several reports of this happening. The biner prevents the rope from completely coming out of the device, but you better hope it's through you (i.e. ascender or gri-gri you are using to haul) or as in the case of the accident it will let all your slack out and possibly strip you and your anchor from the wall.
Additionally as mentioned, you do have to give the thing freedom to pivot around as you haul, or the rope can come off the pulley and wedge between the front plate and the pulley. The biner in the bottom prevents the rope from coming completely loose, but you're still in a world of hurt to fix it.
Play with a pro-traxion with a biner in the lower hole and see just how much you can still open the device with it in place. It doesn't do much.
It is not a bad device, but it should not be used for very large loads, should be watched very carefully. I have stopped using mine and went to a big pulley plus ascender combo.
Thanks for that explanation Moof. That actually clears quite a bit up. Maybe i better rethink what i'll eventually get to haul big loads.