I'm with frogfurr: I have both a 550B and the Redding T7. I load all my higher volume stuff; pistol/revolver, 5.56 and 300BLK on the 550. For my precision rifle rounds: .308WIN, 7MM-08, .260REM, etc. I use the T7 as I like to weigh each and every powder charge for them, and carefully examine each and every round as it is produced. I could probably do the same on the Dillion, but I just like doing it on the T-7 more so because it offers more visibility for that type of work, and I like it's solid "beefiness".
I really enjoy loading on both of those presses quite a bit, especially for the specific calibers/functions that I'm using them for.
IMHO, Dillon, although pricey, completely stands behind their products as alluded to an above post. Perhaps only RCBS has the same, or better, customer support. I have found my Dillon to be very well-built; and when set up properly, it just runs, and runs, and runs....
Personally, I've never had to call Redding for warranty on any of their stuff, and find it all to be 1st class.
IMHO, the Redding T-7 Turret is the beast of all turret presses and will last you and your offspring for a long, long time IF taken care of properly.
On the flip side, there are some long-range precision/competitive rifle shooters loading on Dillon 550Cs.
I don't think you could go wrong with either approach you take...both are top notch. Seeing where you're already invested in a 550, it may behoove you to develop that route.