I just went through well over 1,000 of the GTzip bags. They did hold up fine and certainly served their purpose. I think one or two out of the lot were defective. I don't believe any of them split at the seams. They are 1/2 the price of laminated barrier bags, but the I think the old say of "you get what you pay for" applies.
The negatives I find with these bags are:
They are not as clear as laminated barrier bags and therefore the baits do not look as appealing.
Labels do not stick well.
They do not leak however they are not air tight. Most scents will get tacky when left out. I believe the baits get tacky because these bags even though they did not leak they are not air tight.
If you are pouring for yourself and your friends, the 4mil GtZip bags will do just fine. If you are selling baits, I would suggest the laminated barrier bags. Just the appearance of the baits alone are worth the extra nickel!