  In this short paper we apply some recent techniques developed by Schonsheck,
and subsequently Carr-Harper, in the context of operadic algebras in spectra --
on convergence of Bousfield-Kan completions and comparisons with convergence of
the Taylor tower of the identity functor in Goodwillie's functor calculus -- to
the setting of retractive spaces: this arises when working with spaces centered
away from the one-point space. Interestingly, in the retractive spaces context,
the comparison results are stronger in terms of convergence outside of functor
calculus' notion of "radius of (strong) convergence" for analytic functors. In
particular, we give a new proof (and generalization to retractive spaces) of
the Arone-Kankaanrinta result for convergence of the Taylor tower of the
identity functor to various Bousfield-Kan completions; it's notable that no use
is made of Snaith splittings -- rather, we make extensive use of the kinds of
homotopical estimates that appear in earlier work of Dundas and
Dundas-Goodwillie-McCarthy.
