I haven't used any other product other than Duracoat. I've used it 3 times. Each time I get better at it. The thing to keep in mind is no matter which product you choose, the "prep" is the key. If you don't prep it well, it won't adhere to the gun.
My 3rd attempt was pretty darn nice. I applied 5 layers and let it sit for 10 days. The coating is almost scratch proof.
I attended a SAR show in Phoenix, AZ a couple of years back. I met with a lot of the duracoat people and have seen and touched their finished on a variety of guns. They were not new guns, but very used guns. They seem to hold up well. They did recommend that once the gun is fully coated, you should apply the clear finish to add more protection. I agree with this.
On another note: Two of the guys were wearing a camo shirt. The shirt was a white shirt but was painted into a camo pattern using the duracoat product. The idea was to show how durable it was and how flexible it was, too. Not sure if this is any real test... probably not, but they did a great job doing the ACU pattern on the shirts.