I've owned and loaded on both the Lee Load Master, and Dillon's 550B...here's my take on both.
Lee Load Master, uses a lot of plastic and pot metal parts. Some work well but the primer feed mechanism in particular is a royal PITA. Constant breakage. Lost track of the number of small parts in it I replaced. The powder measure uses a number of varying size discs to measure powder; all of which leaked to one extent or another. The case feed mechanism was difficult to keep in adjustment for hand gun brass...another PITA. After 5 yrs of parts replacement (at my expanse) and constant problems keeping it running...I retired it.
Dillon 550B...SUPERB customer service...two rings, they pickup and answer any question...agents are reloaders themselves and UNDERSTAND the machines. Immediate parts availability and sent at their expense, even those that I screwed up, (one spring crimped and admitted same to the agent). Setup is easy, adjustments were virtually non-existent...ie, the machines were factory setup properly..and a production rate of 200 rounds per hour for hand gun rounds. I now own two of them...one permanently setup for large primers and one for small. Quick caliber changes...less than 5 minutes. One drawback is that the adjustable powder measure, like the RCBS Uniflow, while fine with ball or short stick powders, crunches the long stick ones (3031, 4064 etc). But I've even had good luck with those after polishing some of the working surfaces in the measuring slide and drop tube. I now use it for my .223 rifle rounds used in CMP/NRA National Match across the course ammunition.
All in all, if I were you, I'd save up for the Dillon 550B; you'll never need to upgrade, nor be frustrated by a balky press. I've been reloading my own ammunition since 1962 and have owned 8 presses; everything from a single station Herter's #3 to a costly Herrell turret and have come to the conclusion that the Dillon's just can't be beat for the money, ease of use, reliability, and customer service...if you're looking at progressives, they're the best in the business in my opinion.
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An Loc, lll Corps, RVN, 69-70, Vietnam Vet '69-'73