For years I have successfully used the modern KMC chain for 6 and 7 speed setups. I found an explanation on the KMC website that almost all their chains require the use of the enclosed master link. Well I have been ignoring that advise, and using a Park chain tool to break and reunite the chain for yearly cleanings and original installations. I never have had any problems because a second pass with the chain tool pushing the pin in the opposite direction loosens all sticking problems. Last month I was reinstalling a Sedisport chain after a cleansing bath in brakecleaner. Strangely the link stuck no matter what I did... twisting.... pintooling etc. Finally I took a small screwdriver and pried the link from the inside. Instantly the link freed up. I do however have only a 24 cog on my largest "mountain set up" rear freewheel, because I no longer live in Mission hills in San Diego or Mt Sutro in San Francisco. Skipping chains is not something which I have experienced in recent years due to my ability to run straight blocks most of the time.
Garth Libre in Miami Fl.