I Just finished printing mine at 300% size.
Took a few days and only had one part fail.
It's between 150.7mm-154.1mm, there's a lot of space between the parts at this size.
I'd considered printing it at 700% size, but it'd take a month to print all the parts, and the tolerance between the parts just wasn't meant for that size, I doubt it'd even stay together.
I'm content with my 2 inch and 6 inch companion cube.