One ring to rule them all?

[Jonathan]

Using HIWIN HG25 linear rails http://cnc4you.co.uk/resources/Hiwin%20General.pdf
basic dynamic load rating (lowest rating)
26kn / 2600kg. At a separation distance of 300mm and 1m Z that would be 780kg or 7800nm (but there is 2 of them so this times two really). Clearly the linear guides are adequate.

Adequate in terms of load rating, yes, but adequate in terms of stiffness ... you need to work that one out. There is stiffness data available from THK if you dig around.