I bought one last week and although I've only tried it on 22LR for rabbits I have to say that I'm very impressed, I'm sure it'll be fine for CF foxing as I could easily see to the other end of the field some 250 yards away. The ability to be able to move it from rifle to rifle and record what your doing simply by pressing a button on the unit is an added bonus.
I've had DIY E700 add on, yukon photon (old & new), Nitesite NS200 and a Pulsar N550 and this is by far the easiest to use and as good as any of them. Only draw back is the small field of view as my scope was a x5 mag so I might try it next time with an external screen attached to use for scanning and spotting (connector for external screen is already there).