Well, I have the 4 X 7.5 Excellerator coil, that seems to get very good depth for its size and have been using that. I just don't know if the purchase of another small one would be that much better. Of course, results speaks for itself, and maybe one more coil to the arsenal would be wise. The places I've hunted this year (with very little results, unfortunately) are areas that have produced well in the past but are pretty darn clean by anyone's standards, so I opted to go for depth as opposed to darting in and out of trash.
So, one last question...are you hunting Iron Mask in all metal or are you using a little discrimination? I've managed to teach myself (thanks to NHBob , Tinfoil, and Mike from VA beach) to hunt in all metal and mentally train my hearing to just listen for the higher pitched sounds when I do hit an area with lots of iron or nails. Old fairgrounds are a good example...lots of nails and pieces of rusty wire down there from the construction of what I believe were either temporary buildings, booths or stock pens used at the fairs. What still gnaws at me though, is wondering at what depths I might expect to start finding Barber and Seated. I always envision them at 8 + inches and then start doubting the smaller coil's ability to punch down that far. We don't have really mineralized soil here in SE Minnesota, so maybe those old silver coins are in fact hiding at shallower depths after all. You just never know the "see-through" capability of your machine until you have recovered a few keepers under those conditions...
Again, congrats on the finds..
Knipper