Terry is right, if you try to separate pulltabs and beer caps from gold, you will lose at least 50% of (all) gold, and especially large men's rings. All three detectors are vastly different from each other, so don't buy unless you try, and research, research, research. BTW, if you have somewhat red or dark slate colored soil (magnetite or hematite) you should get the Omega. If not, the Vaquero would be the best bet. Get a magnet, run it through the soil with many passes through it. If you get lots of iron stuck to the magnet you have a lot of Fe in the soil, hence the Omega will be best of the three, but still not the best for high iron soil, because a dual frequency works best for coin hunting in it. If you don't have high Fe, you would like the smooth-running Vaquero, it being deeper seeking than the other two in milder soil.. If you like complexity, good depth, a jumpy needle, a short battery life, and digging lots of tinfoil, get the 705. Yes, the 705 finds some pretty small gold/silver deep, but so do the other two.
For myself I would opt for the Omega, but your situation has different requirements, especially since you already have a rather nice one, the Cibola. If I were you I would buy the slightly deeper Vaquero, sell the Cibola, and then get the Omega when you have the money. If you hunt salt beaches you need a completely different detector than all three of them.
Larry