Ian - Let's suppose one mixes 1L of Ilford PQ Universal and 1L of Liquidol. If the person made 10 prints then bottled up the working solution and then 6 weeks later decided to print again, would they have to mix another batch of Ilford PQ Universal? My experience suggests, that Liquidol would be fine, can that be said for the Ilford PQ Universal? The fact sheet for Ilford PQ Universal says mixed working solution bottled lasts 24 hours. If our OP is a small potatoes printer like me, the difference between Liquidol and the others is noteworthy in this regard. Lasting on the shelf is one metric, lasting mixed on the shelf another. If we assume that both PQ and say Liquidol might last undiluted the same amount of time (based on your experience with PQ), then the consumer might want to consider the longevity of mixed developer as a possible advantage of Liquidol....

Why is this bit something the consumer should consider? Print developer is not one shot like say film dev (eg Rodinal).