10 months ago when you joined this forum you told us you were new to detecting?
Since then you've told us that you have owned a Xterra 305, Go Find 22, SD2100, SD2200D, GP Extreme, GP3000 & GPX4000 + had experience with Nox800 & GPX4500. Have I missed any?
In that short frame of time (+ your stated infrequent trips) you wouldn't have spent enough time on any one of those PI machines to fully master it &/or gold detecting IMO.
Not long ago you were using the GP3000 & had also purchased a GPX4000 + had a deposit on the SDC2300. What happened to them? All of these would be better overall options for gold prospecting in WA!
The Gold Monster is more of a niche type detector suited for milder areas & has good small gold sensitivity. It's not really a good allround type VLF detector.
If you want an allround VLF machine to cover coin/relic + some prospecting then something like the Nox800 would be a better option over the Gold Monster IMO. If you've had previous experience using one it should be a no brainer at a similar price point.