I had the X terra 505 and it was a good machine, you have to be slow and low though..
I have the T 2 SE and it is by far a better deeper machine.. Yhe Visual Id though can jump but generally at a good depth, normally exceeding other detectors capacity, I have dug some jumpy signals but they just sounded right and hit very old finds. A bronze Roman sesterius 177 AD at 8 Inches, as well as a handfull of other coins, I had allready hammered that site with an Ace 25o with a SEF coil, Xterra 505 and a G 2, but the T 2 still produces, I think you will be hard pushed to find a deeper VLF machine.
I run mine at 70/80 sensitivity only 04 Discrimination, and 2+ tones...
As it is proven fact, discrimination kills depth and because in 2+ tones the detector will give a dual tone signal, gront on iron & squeek on non ferrous, there is practically no need to run it with high discrimination.
I use an Ultimate 33 Detech double D coil on mine.
Yes the signal sometines is a little jmpy and the machine is a little chatty, but I prefer a machine that fnds signals beyond the majority of the others, jumpy or not, it does pick up signals others just don´t..