I own the fixed circulars as well as sets of interchangeables and they are all of the highest quality. Even the finest yarns glide past the unions. After learning Cat Bordhi's two Circ method, now I have a reason two buy two of every size!
I love the little short circulars for making sleeves ... they are a bit tight if you have big hands which I do not and a bit fiddly when binding off I switch to a second needle for that ... other than that ... I have them in all the sizes up to a 5mm I think ... they beat double pointed needles for sleeves anytime.