Just bought a RL550C for my 6.5CM. I was tempted to go with the BL, and should have in hindsight. I knew I was going to drop the powder using a funnel in station 2, so don't need another powder measure. I have several of them already for my 650 and 1100. But I thought the auto primer would be worth it. For the extra money, I still feel like those extras justified it. But it's not doing a great job of seating primers (CCI BR's) in my very clean or new 6.5CM brass, so I went back to hand priming them anyway.
The main reason I went to the 550 is the much more consistent OAL, which it has done a great job of. I don't want to go to a single stage, so this is a nice compromise.