I was out today at the park comparing a Fischer CZ-7a Pro and a F-19. I think every detector is fun in it's own kind of way. I think you will really like a machine that has VDI numbers. With a beep and dig, the signal may be just a little erratic and you will never know it. With a VDI machine if the reading is pretty steady, it is most likely what it says it is. The ability to tell what an object is requires a lot less knob spinning. From the Youtube videos I see the F-5 is a fine machine. I thought about adding one to my collection but then a duel frequency machine came up and I went for it, (Whites DFX).
I am a big fan of a designer named Dave Johnson. He worked for a number of manufacturers and had a hand in some of the best machines made. A short list, Old Fisher: 1260, 1220, 1210, 1225, 1235, 1265, 1266, 1280, Impulse, CZ6, CZ5, CZ20, Gold Bug, Gold Bug II, TW6/Gemini, FX-3, and several industrial products. Tesoro: Diablo MicroMax, Lobo Supertraq. White’s: DFX, Beachhunter ID, GMT, MXT. New Fisher: F75, F4, and everything else since then. He now works for First Texas which is a parent company of Fischer labs. I think anything they now make will be something worth owning.