My only experience of either is on aircraft work (apprentice aeronautical engineer) and i prefer clecos as they are much quicker/easier to use. The have a strong spring and pull the skins together very effectively, as opposed to hand tightening the collar. Don't forget you fill require the cleco pliers as well.
Hope this is of some use
Alex
Unfortunately i'm not able to help with the request but for anyone interested in converting their series to RRC axles i have a pair in wiltshire already converted just needing paint and new brake lines making that are yours if you can collect!