I think the carbide dies are useful for commercial reloaders but not the average shooter (even those who shoot a lot) in that they last longer, but they are sizing thousands and thousands of cases. The amound of wear that brass inflicts on steel is very slight, and if you're not doing it thousands of times a day, save the money. I use Dillon products more and more because they are top quality and they stand behind them, no questions asked. Most of the other companies do as well, and I have RCBS, Pacific, Lyman, Lee and a lot of others that work swell. But I have an RL 550 that runs like a BMW and Dillon has helped me out significantly over the 10-12 years I've had it, both with patient step-by-step advice early on and occasional replacement of parts that I thought were defective, but which truly were not (and I think it was apparent to the rep but he never flinched at replacing them). I don't think you can go wrong with any of the major companies; I tend to like Dillon for reasons stated, but don't use their bottleneck carbide dies (straight wall pistol dies is another thread!). Mis dos centavos...
(P.S. I usually order for DillonPrecision.com, or call the 800 number)