I'll throw in my two bob here.
For ~4 years I used my 11" Commander mono that came with my old 4500 and was averaging over 1g per find in the GT and in later years, did quite well. Really got to know that old gal, although she's looking her age (but still works a beaut).
My mates with all their coils often marvelled at how well we (my daughter and I) did with it - generally coming home with a nice haul.
But the hype of the new super sensitive coils infected me. I then bought the 14*9" Evo, which I soon discovered had great sensitivity on smaller stuff, and we soon started finding the tiny stuff - cool. We were encroaching into SDC territory.
For the past nearly 2 years it has been my "go to" coil, but my average weight per nugget dropped down quickly, as did my average total gold weight per outing. Yes, my nuggets per trip increased, but the average gold weight per trip decreased dramatically.
I'm asking myself, is that what I bought my 4500 for, and am now seriously thinking of changing back to the old Minelab 11'Commander mono in the GT (certainly my daughter wants me to and regularly tells me to!!!!).
Why? Less sensitive to hot rocks/ground. The bigger gold stops us with the 11" Commander - not the smaller gold, so by missing the fly shite, we cover way more ground between digs, have a greater chance of digging bigger nuggets (like previously), miss digging every single lousy bird shot and being fresher at the end of a long day, so more hours put in.
In retrospect, I should probably have stuck with the 11" Commander (plus maybe a larger one for the rare times that I get onto deeper ground), and saved a few $k. It's hard to shake the infectious hype that surrounds us like flies/mozzies though.
It seems like I have this amazing ability to realise the obvious a long time after my kids do