New interesting answer to screw whip.

[JAZZCNC]

I would hate to think what 2x 3mtr ballscrews would cost, I take it a support system to prevent screw whip would add to that cost as well

Not much as you probably think if got from China. If done correctly no support system is required and no whip will occur.
If wanting really high rapid feed rates then does start falling in R&P favor because does get difficult to handle whip with ball screws without going to rotating nuts.
But if can live with 15-20mtr/min rapids then ball screws can be made to do this without the whip and no pratting with rotating nuts etc.