Ok, so the only one I bought was the Tesoro BII uMax with the 8" donut.
Then a month ago I inherited an older White's XLT which I had borrowed before and used for nearly 700 hours over a 3 year period or so.
Then I also at the same time I inherited a repaired and rarely used older Excalibur 800 with the 8" coil.
So when I went to an old inner city sidewalk repair I took the XLT with the 3" by 5" DD shooter coil since I felt that it would give me good coverage (all be it very narrow) and good separation, and I am very used to and confident in my abilities with the XLT. So what I found was an 1872 IH penny, an 1892 V nickel, a 1902 V nickel, an 1896-s Barber dime, and and 1898 plain Barber dime.
I went back later in the same day with the Tesoro with the 8" coil (yes I had already purchased the 5.75" which has also done well at this site) and found 2 more IH pennies, one of which was smashed and buried in the same hole with 3 nails, but the "signal kept screaming dig me up, I am a coin". The other IH penny was an 1892. And the particular spot had already been gone over by me at least 4 times before. Maybe "it really pays to dig up the trash and uncover the masked signals".
For safe measure I tried to use the Excalibur800 the next morning and all I found was an 1917-s Wheat Cent.
But I am still learning the Excalibur and only have about 30 hours behind it.
I shudder to think what I might find with either an Explorer SE/eTrac, or with the new White's Spectra V3.
But I am doing OK with what I have.
The main thing for me is being aware of the sites in your area and doing the necessary research to be "johnny on the spot" when construction opens up possibilities for you.
Of course I have also visited this site in the past many times in a row with nothing but nails and bolts to find. Then "pazoW" I find something nice to make up for all the frustration.
So persistence also plays a major role in getting the best results.
Took the XLT to a large inner city park a few days back and may have my first gold coin (in a pendant and the writing seems to be Chinese). I am still trying to get a good picture of it which is very difficult because the bezel is glass covered and sealed over the coin, and the coin is thin and very well worn.
So it would be very fair to say that I believe in using a variety of tools for the job.
But I do agree that the more familiar you are with how your machine works (what it does/what it does not), the better your finds will be.
For instance in older constructions sites and older town parking strips nearly 100% of the Indian Head pennies that I have found came up in the range of bottle cap with the XLT.
TOO MUCH DIRT, NOT ENUFF TIME!
nwdetectorist