I am going to disagree Irving, i have a full set MT3 metric and imperial for smaller mill mixed 3/8" and M10 from Arc using two draw bars.
On the larger mill i had specific imperial and metrics with M12 thread. I regulary held 1/4" in 6mm MT3 collet likewise 10mm in 3/8" collet, 12mm in 1/2" etc, mine do clamp around 1mm smaller and larger from Chester and Arc Euro Trade. Now got full set down to 3mm and up to 3/4".
http://www.youtube.com/watch?v=Uy8zQ-h4F8I
Mach 3 tool change set up http://www.youtube.com/watch?v=0cM32grBMvo

The ER type from Chester at work are absolutely not worth the plastic box they come in, grolly them up two spanners mate used to annoyingly use a hammer as well, cutter drops scrapping job 8 out of 10 times putting around 3mm cut on. Even when cutters have dropped they are a pain to undo.
May be down to the chinese producer i have had more than my fair share of crap from Chronos namely their interchangeable German sounding tools, RGD and Gloster are good but usually stick with Kennametal or similar.

Regularly hold drills in increments of 0.1mm in collets, less runout and extra height gained!