For what its worth, all kilo fish at the comp the other week bar one were caught on lures other than gulp from my knowledge. I got one on a sandworm that i threw in to basically see how bad the blowies were. But hey i will take it. I think and im sure nobody will disagree that your at a disadvantage if you dont at least have it on board in case you have trouble getting fish in a comp. But socially you should be trying to get your technique right so you dont have to resort to gulp in the first place. All of my big fish in last years WABT comps came on lures other than gulp. The 1.4kg stonker at perth round came on a snapback as many regular kilo plus catchers fish with them. Mandurah they came on a hard lure of sorts (contrary to what came out in the mag) Blackwood, berkley 2" grub, though i did fish some gulp that weekend when going got tough.
When your constantly fising gulp, I find that more smaller fish, grunter and blowies hit it rather than the bigger fish you want. It seems blades, snapbacks, critters and marias are the most popular upgrading lure choices. Apart from at walpole where it seems gulps are a major preference of inlet bream. That is a shame, but like i said if your worried that you arent catching fish then use what you want.