The RL450 is the exact same thing as an RL550 EXCEPT, in the original form, it has no removable tool heads, manual primer and powder measure. When converted in those two areas, it functions exactly like an RL550 until you go to do a caliber change.
So, if the RL450 qualifies as a turret press, so does that RL550. That ought to get those RL550 owners talking!