I think this is a fair comment up to a point, however, a dedicated denomination collector will in all probability try to get an example or two trophy pieces. Obviously this depends on the criteria set, but a collector of bronze pennies for example may well want an example or two of a proof bun head, or a G5 VIP assuming it is within their financial resources. For all the reluctance of many to get involved with proofs and patterns, their value tends to hold up well and are probably more suited to the investment approach in any case as their values appreciate slowly but reasonably surely with time. This is another reason why the odd proof or pattern is not a disaster for a mainly currency collection. Currency coins may have a greater following, but their prices fluctuate far more between sales.