I often prefer cord to chain and Imm dacron cord from Hobbycraft is the best I've found. Its not perfect but its not bad and cheap as chips.
I wish Gardner sold spare cords for their Nano bugs. That is perfick but it cant be in 2 places at the same time and I dont like moving stuff between bags as the Law of Sod decrees that whatever I need will be in the other bag. It happened to me on Thursday. The bobbins I wanted were 30 odd miles away.
I used Solar indicator with the ball chains not really thinking about it too much until I struck a fish one day and the chain broke just as the indicator came off the line. Up in the air it went and into the water not 6 inches from the bank. Could I find it? I searched for ages with my hands and arms grubbing around in silt and all to no avail. Since then I've used chains and really heavy ones on Nash indicators, but these days I tend to use just one rod as a sleeper and that has a titanium spring based indicator and damned good it is too.