I do not think the new X-705 has more sensitivity horsepower. It is the same as the X-70.
Let's see for hunting iron sites I learned here:>> Notch out noisiest iron segment, sometimes sensitvity down, use the 6 HF DD, Tracking on (the tracking does settle the iron falsing down to nothing!!), and wait until the ground dries out before hunting iron sites.
P.S. As Digger(Randy) wants and we do now need a 6 LF DD(and 10.5 LF DD) very badly for hunting these iron sites. Of course there is the 9 LF Concentric we can use now. Digger proved on a test in a previous post that the LF will pick up a fine-small gold ring just fine so you will not miss small gold jewelry with a LF if that is what you are worried about!