Sure, for what it's worth. I used 600mm smooth rods and the spreadsheet @mjrice provided to get the extrusion sizes needed. I ended up with 413x417x440 build volume. It has a 350mm^2 800W A/C heater on an aluminum bed, which provided a couple of interesting problems to solve (induced current on the aluminum plate and bed expansion). It heats up insanely quickly (in the center), but still have to wait for the entire bed to finish heating, otherwise there is some very entertaining warping that happens - > 2mm.
I have problems with Y movement vibrations, and have to be careful with the slicing to minimize it. Jerk is the issue, coupled with the print velocity. I'm switching to steel cord belts, as I can see a +-Y movement difference in the vibrations. I've ordered some toys from Adafruit (data logger, accelerometer) so I can characterize the vibrations and see objectively what further changes help. I've already switched to 1/4 steps, a 0.9 degree stepper motor, SilentStepStick driver - which is awesome BTW, and 16 tooth drive gears, which have all helped some. But I wasn't really having problems with stepper slippage as I figured out later. The bed overhangs the rail mounts so much that it flops around with the Y jerk directional changes. Acceleration governed changes are fine. It's really interesting to see the dynamics of the shake, as it's hard to tell where the problem is coming from. The build table doesn't feel floppy, but it is under the correct circumstances, it looks like a diving board. It'll be interesting to see the accelerometer readings.
I'm fairly sure as the Z print height increases, I'll start having X sway problem, and will be adding upper corner bracing to address that, maybe with a second cross beam.
To make it more stable overall, I'm thinking of increasing the X and Y footprints by widening the extrusion mounts (i.e. most of the printed parts).
I have hopes of adding a bowden extruder, or maybe a E3D Cyclops/Chimera, for dual color printing.
Overall, it's nice to be able to print multiple pieces at once, each one to completion before starting the next (via Simplify3D). I ran across Plater, which does an excellent job arranging optimal build plater(s) for STL's you give it. If I was so inclined, I could print this clock in one go. I might be inclined if I don't need the printer for a week or so, and get a filament runout sensor going.