I used 25mm OD ballscrew with a 25mm pitch for mine, and with the motors I've got, I get 18m/min, which for about a 1.4m run gives ~4.7 seconds for total travel. However, you will need to worry about whip.

Gary (from Zapp) gave me a website which allows you to calculate the whip speed based on the diameter and so forth - unfortunately, I've only got the link at work, but Gary may come on here before I get the chance on Monday to get it.