The Fisher F19/Teknetics G2+/Time Ranger Pro are outstanding relic detectors in thick iron or for just normal relic hunting. Personally however, I think I would prefer to coin and jewelry hunt with your Simplex. And the Simplex wins for waterproofed and wireless operation too. My testing of them head to head was about equal for sensitivity to small targets, target ID accuracy and depth.
The discrimination mode on the F19/G2+/TRP is fine except for the lack of multiple tones like there are in Park 1 and Park 2 on the Simplex. I have owned both so these are not unfounded opinions. They would make a good combo. The threshold based all metal mode on the F19/G2+/TRP is as good as it gets in my opinion. That is why they are great gold prospecting detectors too which is what they were originally designed for = Fisher Gold Bug, Gold Bug DP and Gold Bug Pro.
If the F19/G2+/TRP had at least three tone audio in discrimination mode they would be incredible all around detectors and a lot more people would own them for sure. I love the virtually EMI proof 19 kHz operating frequency.