The Duotone Echo has an excellent range. I don't think you will find anyone who thinks its range is less than that of any other good quality  wing, boom or center strut. I have a 7m and a 5m and there is plenty of overlap - I've never had a day that I thought I really needed a 6m - although it would be lovely if I had the money
Having used the Echo, and a fair few wings with center struts from other brands, I haven't noticed any difference in frontstalling when overpowered, in fact I felt that the Naish s25 (v2) was more difficult to control when overpowered than the Echo. Maybe it was an issue for the Duotone v1, but like I said before I can't comment on the v1 as I haven't used it.