The Supertraq is a gold machine with that higher frequency and all, actually designed to find nuggets but like all Tesoros can do fine on coins, jewelry and anything else.
In your case using your parameters and choice between the two you listed I would think the Lobo would be a bit of overkill.
I have found a lot of coins and gold on land in the mostly public parks I tend to hunt and I did it using several detectors...
A 13kHz F70
A 14kHz Vaquero
A 12kHz Compadre
And an entry level Fisher F2 with a low 5.9kHz frequency...found about 2 dozen pieces of gold with that one and many thousands of coins.
All of the gold I have found has never been deeper than the normal range I have found most of my targets from shallow to about 5-6".
Gold is rare are thing but it is out there and opting for the Lobo just because it is a little higher frequency isn't logical thinking to me because most detectors will find coins and gold at normal depths and situations.
The chances of that Lobo finding gold others can't in the real world isn't all that high if you crunch the numbers...some nuggets smaller and sometimes deeper yea maybe, normal gold rings, religious medallions, pins and other jewelry not so much.
The Cibola is a killer on coins and jewelry as is it's brother the Vaquero which is the same thing with the added ground balancing feature.
That GB ability might not matter if you hunt in good soil but in some hotter dirt with a bit more mineralization it could matter in some situations and get you a bit deeper although plenty have found tons of coins and gold with both kinds of units over the years...fixed and adjustable GB.
As far as pure depth I would be looking at the Cibola, Vaq and Tejon because they have great track record in that area but all are capable and can get pretty deep...depending on your soil type of course.
Plus all the other Tesoro units are very good at finding all of that stuff too...when I am in a jewelry sort of mind I would opt to use my Compadre or Mojave as much as anything else because they just work so well at these tasks.
When choosing a tool the best thing to do is pick one that has features that have advantages that can help you in your sites and situations and make hunting more pleasurable and fun...for you.
It sounds like you are aiming to hunt public sites like I do so in your case that slightly higher frequency feature would not be something I would be so concerned about at all.
A non-issue...for your needs any of their models will work so pick one out using other feature criteria.