  New arguments are presented to emphasize the interest of the infrared finite
coupling approach to power corrections in the context of Sudakov resummation.
The more regular infrared behavior of some peculiar combinations of Sudakov
anomalous dimensions, free of Landau singularities at large Nf, is pointed out.
A general conflict between the infrared finite coupling and infrared renormalon
approaches to power corrections is explained, and a possible resolution is
proposed, which makes use of the arbitrariness of the choice of exponentiated
constant terms. A simple ansatz for a 'universal' non-perturbative Sudakov
effective coupling at large Nf follows naturally from these considerations. In
this last version, a new result is presented: the striking emergence of an
infrared finite perturbative effective coupling in the Drell-Yan process at
large Nf (at odds with the infrared renormalon argument) within the framework
of Sudakov resummation for eikonal cross sections of Laenen, Sterman and
Vogelsang. Some suggestions for phenomenology at finite Nf, alternative to the
shape function approach, are given.
