In my Pennsylvania soil the dd coil outclassed the concentric coil,,it goes just as deep or deeper,and way better separation.
I’ve had the sharpshooter coil on the 705 ,,and it’s one of the better coils for that machine.Runs stable,good depth and awesome separation.
Some people don’t like nel coils for the xterra,because of personal reasons outside of performance.Myself,I use what works best,and although Minelab makes some good coils,so does Nel.
The 10.5 Minelab Coil medium frequency is the one Id get if I only had a 5x10 ..You already have a good sized coil for sidewalk strips and smaller places, the 10.5 will get you coverage and better depth in more open places..
Thing about that xterra is don’t get caught up in too many coils,you’ll have more wrapped up in it than a Etrac..