How many miles you should expect to get from a chain before stretching to 1/16"/ ft varies from rider to rider. I use Record 5.9 and D-A 7700 chains and always get more than 5000 miles before a 1/16" stretch. I have never had chain skip and have never worn out a cassette cog or a chainring.

I prefer to follow the instructions and use the recommended special pins and special links for joining the chains.
I think nickel plated chains can last longer and do look better on the bike. I cannot confirm that they are more cost effective.

Recently a friend asked me to help him tune up his bike. The 10-speed Ultegra chain was making a lot of noise and not shifting smoothly. The chain was stretched 3/16"/ft. He checked his records and said that the chain had nearly 9000 miles on it. The cassette looked pretty chewed up so we replaced both.

Al