Yes. I've worked at a few world scale ammonia plants so know what copperslip contains and why alternatives are required.Copper slip is "Copper grease is a specially formulated anti-seize compound manufactured by combining fine copper particles and high grade corrosion and oxidation inhibitors. The grease is created through a procedure that combines oil with soap." So contains a lot of oil. The soap will either wash away, or react with calcium in the water to deposit the scum on your line that you get round the bath if you live in a hard water area.
My experiments: I got polyvinyl alcohol (PVOH) to dissolve in water but adding IPA or acetone precipitated it. So still need an alternative to water. Don't fancy methanol as it makes you blind! I also tried dissolving solid polyvinyl acetate in toluene. After 4 days it was still stuck on the bottom! So again still looking for a more volatile slovent than water. I've gone back to making the PVA/Fullers earth paste, but now added a little glycerol to stop it from solidifying so quickly. Next time I'm out I'll compare it with the usual detergent/fullers earth/glycerol mud.
OK, that is what I often do, though it may be a small PTN, but if the club rules say one fly only?As I've said before I prefer to fish with one fly and with fluorocarbon leader and tippet, if there's no ripple I'll use a little buzzer on a dropper, this sinks the line while allowing the fly to float.