I have both a 550B and a XL650. Also had a 1050 for a while. If you are going to load lots of pistol rounds get a 650..but if a mix of all the rounds mentioned get a 550B. It will load all you will need and although it operates at a slower speed...how fast do you need to go. My Dillon 1050 I bought at an auction for a ridiculous price...350 bucks. I had about 1400 once fired 45 auto empties so decided before I moved out here to load them. It took me less than 2 hours from start to finish. Sold that darn loader for a heck of a profit and never looked back. I don't shoot them that fast and I'm not going to get into competitive shooting anyway. The 550B I also bought for a very low price set up in 45 auto but switched it to rifle and it will do most of what I need for rifle cartridges. The 650 is set up in 45 auto with dies for my other pistol calibers...except 9MM. It's so cheap to buy I don't load for it. Look on ebay for a loader set up the way you want. You may be able to find a good buy. BTW the Dillon pistol dies are excellent...not Redding but they will do all you want. A friend uses a Dillon 550 for almost all his loading...except load development in rifle ammo. Only person who's reloads I'll shoot. Course I set his loads up for him.
Go with the 550...you won't be sorry! BTW you may want to rethink the 300 Win Mag on a Dillon. How many do you shoot?? Also..keep a single stage press for load workups...JMHO