The recently proposed hypothesis of two incompatible mechanisms of chain growth based on CH2- and CO-insertion is furthermore supported by a detailed interpretation of the (CH2N2)-C-13 co-feeding experiments of Maitlis and co-workers and of the selectivity of branched hydrocarbons. The carbon number distribution is discussed considering in particular the role of readsorption and incorporation of 1-alkenes and its subsequent chain growth. (c) 2009 Elsevier B.V. All rights reserved.