Hey DakarM,
Don't apologise! I very much appreciate your input. FWIW, I've already decided that when I get coilovers for my M3, they'll be double-adjustable. I am open to DAs. However, I can't find any koni DAs online, and without prices, I can't make a decision.

Now more questions for everyone:

I don't know enough about the GC sleeves. I do know that I can get the GC sleeves and koni yellows for $339 + $600 = $939. Or I can get a koni coilver kit for $1299. What does that extra $360 buy me?

Also, is it worth considering coilover kits from companies like APEXi, B&G, Cusco, D2, H&R, JIC, Tanabe, Tein, etc.? With the exception of H&R, I know nothing about those companies.

Thanks again!