Which Tesoro you looking at?
I have tried the Compadre, The Silver Umax, and a Tiger shark. And this is just my Noob opinion.
The compadre is great little detector for parks/tot lots, and other areas that can be trashy. I like mine with 5.75" coil easy to pinpoint, Light weight and really has pretty good depth on coins in the park. Its not the best in sand (fresh water) or in the water. It works, but the AT pro will out shine it here.
The Silver Umax to me was pretty much Like the Compadre, only it works better on the beach, and has slightly better depth, but that might be because it came with 8" coil. For me I had heck of time Pinpointing with this Machine, there was often times I dug big pugs just to find the item in the side of the hole it was frustrating at times. On side note, my best find so far was with this machine.
My latest one is the Tiger shark, So far I'm just loving this machine, Its great on the Beach and its great in the water (fresh) since its fully water proof, Its a bit heavy after awhile, but mounting the control box to your belt solves that problem.
I know its a water machine but I use it on land and in parks more than the water, and man is this thing sensitive in all metal mode. Today I was hunting some farm land looking for relics, And got this light chirp from it, The Tiger seems to have 2 tones to it. A Light tone, which usually means the Target is deep or really small. Or a loud tone, which means its something like a coin and with in 6 inchs of the surface.
Any way I was getting a lite chirp from it, and I thought maybe it was deep coin or shell case-sing. Turned out, about 4-5" down in the dry dirt, it was 1 super small bb pellet from a shot gun.
For me the Tiger is supper easy to pinpoint, just lift the coil up, and you can get idea of the depth and pretty much nail it on the head where the item will be, works well for coin poping.
My only complaint about the Tiger shark so far, is it Loves tin foil, and them little tin tips pencils use for there eraser. You can kinda tell when its tinfoil most of the time, because the tone wont be clear in all directions, but if its smashed right it chimes just like a coin. School yards can be a nightmare with it, until you really learn it.
Just my 2 cents so far, hope it helps.