From the base of the machine the case feeder adds:

RL1100: 39.5”
XL650: 35”

Plus whatever mount height you have. I’ve the RL1100 on a 4” Inline press mount and the XL650 on a 9.5” Inline Fabrication press mount. I have a 36” bench so the tallest setup from the floor is 81” and puts the shell plates at about 51” which is great for me for standing to reload.

Of course you’ll need clearance above that to add brass and room to change case feed plate for different calibers.

I have a Dillon RL1050, XL650 and RL550. If I had to keep one, it would be my XL650.

An XL750 gets my vote as well.

To the OP...if you're really set on another press, my vote would be another 550. As another poster suggested, you've already got all the caliber change kits and turret heads. And like you, I have two 550's, one for each primer size; which really speeds up caliber changes. But I've got to ask, why? I can do a caliber change on mine in 5 minutes or less and setting the powder measure...maybe another 5 minutes...not a lot of time savings for some pretty big $. Rod