Starting to design out my build, looking for critique

[Chrono]

If by12m/s your meaning 12 meters per second then your massively off with your settings. 12 Meters per Min is more realistic figure.

To be honest that spread sheet is load of rubbish and spits out unrealistic figures. Real world is much different due to the many variables that affect machine performance.

Ah yes, indeed it is 12m/min, don't know how I have read that wrong every single time...

I have been using the spreadsheet to dimension all my motors so far. Is there a better way to do this, or will it all just come together in the final build? I am guessing there is no real way to account for all the variables the steppers will be influenced by when it comes to it, but I guess what I am asking is: Is it still a good idea to run the motors you can find through the spreadsheet to find the "best one" you can still drive?