The 2.9 does seem to be a little deeper than a 4.0...but Now I much prefer the 4.0 to the 2.9...
though the 2.9 seemd a little deeper ,,,,for depth I use other machines anyway,,,what I find is the 4.0 will unmask better...
it all lies in the target response...
the 2.9 was full on VCO from coil bottom to depth...
The 4.0 is beep out to about 5 inches or so then VCO comes into play..
whe you couple the first 5 inch tight beep with the laser edged 5x10 DD you can pick the slightest peeps out of nails that the VCO audio does not fully relay to you audibly...
Also the All metal gain is more adjsuted to meet the disc gain on the 4.0... the 2.9 required turning back when going form disc to all metal and nothing wrong wiht thta exceptht he I.D. depth falls off when the gain knob is truned back...you can get more i.d. depth in all metal on the 4.0 than the 2.9 with stable operation...
Also in disc mode the I.D. screen clears itself after a few sceond's..on the 2.9 it holds to the next target...why is this problematic....what if the last target you hit was iron reading 23 well you get a hit but tis too deep to trigger the I.d. to change but you look down and see the 23 still there and unknowingly walk away from a good target that was just past the numeric i.d. range but not knowing it...On the 4.0 the self clearing option will not show a target i.d. on too deep of a target so you will investigate to see what it is..
but the 2.9 is a tad deeper if thats what you require...
Look at the strongpoints of each and decide...I use detectors as tool's and the unmasking in iron is more important than the depth on this freq....so I choose the 4.0 now.
Keith