Wow, the X6000A is big! Yeah, the specs say it's 10 feet long, but it just doesn't really come home until you put it together, I guess. It's a couple feet longer than the Comet KP-20, even. And it has much, much longer radials (likely because they have to work on 2 meters).
One of the issues will wind up being how to mount the two antennas. Of course, most of that depends on the site. But despite the cross-band nature of the repeater, it's still going to be desirable to keep the transmit and receive antennas away from each other - either at different elevations on a tower, or 10-20 feet away from each other horizontally. That will obviate the need to set up a 33 cm band-reject filter to protect the receivers.