First question, is the Simplex + your only detector?
Next question, when you say really trashy, are you referring to Modern, urban type trash or is this an old site with a mix of ferrous and non-ferrous debris?
And the further the last question, if it is a lot of nails and other iron trash, how closely associated is all of it?
I ask because I hunt both types, Urban locations with a bunch of discarded bottle caps, foil, tabs and other litter, as well as rural locations to include Old Town sites, stage stops, old dancehall and church sites, and other places that had high use or activity, and frequently have a lot of iron nails and other closely associated ferrous debris.
Depending on the type of trash in the amount of trash, related to the density or closeness of the trash, can make a difference on the detector and coil I put to use. I use the Simplex + with the 5X9 1/2 DD and it works quite well in low two moderately littered sites. When I take on the challenge of very dense iron contamination, then I prefer a smaller size coil on a detector that handles the toughest ferrous conditions.
That would be the 5" DD on my Nokta Relic, with the 4.7×5.2 DD on my CoRe. I enjoy the performance I'm getting with my Simplex + and feel it could provide comparable performance with those two models if it had a 5" coil. Sadly, the folks at Nokta / Makro have not provided us with a good, small–size coil.
I have hunted both city and rural locations with my Simplex + and 5X9 1/2 DD and really like that coil and the performance until they get very trashy. That combination is one of my regular use set-ups because it both balances well and works well.
Monte