I use a 13 year old Explorer XS
The F75 is a fantastic machine for small silver, Doc uses one and I don't think I've been to a rally with him where he hasn't found some silver.....ooh wait a minute, yes I have, Westbury, and then he found a Gold ring instead lol
They have there drawbacks the same as any other machine but they do find the goodies. Machine technology hasn't really changed for 30 years, yes there has been a few fine tunings, but to be honest I was finding as much 30 years ago as I am today. The only true secret to successful detecting other than practising and getting to know exactly what your machine is telling you is to go detecting
The more miles you cover the better the chances of finding something...simple as.
I hear people saying "Oh I never find anything worth finding" and then when I ask them how often they go detecting they say "Oh about 8 hours a month".
Up until the end of July last year I had found 12 hammies in the proceeding 7 months, in the next 10 weeks I found another 18, but this was because I was spending at least 16 hours a week detecting.
Plus you have the added benefit of the more you detect the more machine experience you get.
We all and I include myself, suffer dry periods, and we blame the machine or the coil but then that dry spell passes and we forget about our doubts until the next time.
Remember that this hobby has always been a "micro" hobby and machine manufacturers have to keep producing machines with new "gimmicks" otherwise their market would very soon be saturated and they would all have to close, but gimmicks they are, for if any of the "boost" "deep" or whatever else the system is called, worked, we would all be using the same machine.
I wish I lived closer to you as I would come out and give you a few pointers but if you ever fancy a trip down to deepest darkest Somerset, then your more than welcome.
My advice though would be, keep the Fisher and learn it.