I own a MicroMax Silver and love it. The MicroMax Gold has a few more features, but I'm not sure that they would result in better performance in your situation. What does the MicroMax Gold have that the Silver doesn't?
1) Notch Discrimination
2) Manual Threshold Control
3) No-Motion All Metal Mode
4) 4-tone Audio Feedback
The Notch discrimination is only useful for coin hunting. If your targets are so standardised that you already know their shape, size, and composition (like coins), then notch discrimination will give you the ability to pick out all the coins and leave the jewelry, pull tabs, and so forth. If your targets really are that predictable, then notch discrimination makes sense. If you don't think you'll ever want to ignore everything but coins, then it's basically useless.
Manual threshold control is a nice feature to have (I kind of wish it was on the Silver too), but it's mostly useful for maximising detection depth/radius in the absence of trash. If there's metallic trash under the coil, your threshold-based advantage will disappear. No-Motion All Metal mode is nice (I wouldn't mind having it), but I have a Garrett Pro Pointer, so I already have a short-range, no-motion device.
The most notable difference is the 4-tone audio system. The Silver provides only one tone with a bunch of different qualities. The Gold provides four tones, each one representing a different conductivity (discrimination) level and bearing similar signal qualities to those of the Silver. This is the only one that might be a significant help in target-rich areas. Honestly, if I were you, I would put that money into a specialty coil for the Silver.
Check out this listing from Kellyco (link below). The first section you see will be regular search coils for Tesoros. The first three rows won't fit the Silver, but are only for the higher-priced (H.O.T.) Tesoro systems. The next three rows of coils will fit the Silver. In the section below that, there are the EXcelerator coils from DeTech. Two of those will fit the Silver. Personally, I haven't ever tried the EXcelerator coils, but I've got my eye on the 12"x10" butterfly (similar to DD, but works around a few drawbacks). If I were about to throw $200 at metal detecting equipment, that's what I would get for my MicroMax Silver.
Metal Detector Search Coils For Sale - Kellyco Metal Detectors