I've been digging for like 30 years or so, and being from the "old school"(but not always the best school), I have prefered to always hunt with the stock coils. Only extra coil I ever purchased was a 15" coil for my old Whites Spectrum. Talk about HEAVY. Anyway.....Mainly for relic hunting, and not changing coils, would a 50 be as good as the 70?, and would the stock coil on either machine suffice? Thanks