People have been using cart for years. For those who put the time and effort into making their own quality cart, they will be rewarded with excellent bait, that will catch plenty of fish especially from the rocks.
Best fished in cocktails with crab etc.
I dont know about the mass produced stuff thats appearing in tackle shops, as I havnt tried it, but i'd be wary of whats actually going into these baits, not much crab I expect!