Hi ya Tinman,
I use my own settings on the 4000 and the 5000. I have a mate who uses the 4500 and he uses the setting bellow:
SWITCH LOC 1 SEARCH MODE... G 2. SOIL TIMINGS ...ENHANCE 3. GROUND BALANCE ... FIXED; SETTINGS:-- VOL LIMIT... 12 GB TYPE... G SPEC SMOOTH, MOTION... SLOW, RX GAIN ...12-14 ,AUDIO ...NORMAL, AUDIO TUNE ...whatever tuning brings up, STABALIZER ...12-14 Signal...16, TAR/VOLUME... 12, RESPONSE ...NRM, TRACKING... SLOW,
The 5000 will outperform all before but only just on the 4500 using the Commander 11", great depth on specimens but we are talking bat poop here. I have bits even smaller than a 10th of a gram. Personally, if you have a 4500 I would not upgrade to a 5000 as it only involves the smallest of pieces. The 5000 is better in Salt country on salt lakes but for this you need to run in salt mode with a DD and in cancel. This is a big advantage of the 5000 over the 4000
The best machine I have used for depth on 10gram + was the SD2200 with a 18" Mono. Still a great machine but does not handle the mineralization with a mono as does the GPX detectors.
These are my experiences which could differ from a lot of other detectorists.
Cheers
The 8" Mono nugget finder is good on small bits in shallow ground but will miss the deeper ones if there is depth.