in view of the latest resutls from cladistics models. Quotations follow.
European and Computational Cladistics. By: Ringe, Don; Warnow,
Tandy; Taylor, Ann. Transactions of the Philological Society, Mar2002,
Vol. 100 Issue 1, p59, 71p;
"There are at least two scenarios that might have given rise to the
peculiar pattern of data involving Germanic. One is that the
diversification of the IE family must be modeled at least in part as
a network rather than a tree (as discussed in the previous section), (p.
52)."
"For instance Garrett (1999) whose discussion is unusually clear and
well articulated suggests that various subgroups of IE arose by
borrowing of innovations among closely related dialects which were
not very different from other, neighboring dialects (p. 50)."
"It is possible that the position of Germanic in the IE family is a
problem of this sort, but only if it occupied so central a position
in the family during its early diversification that its removal from
the data would resolve the remainder into a relatively clean tree.
Whether that is plausible mathematically or archaeologically is
unclear to us (p. 52)."
CPHL: COMPUTATIONAL PHYLOGENETICS IN HISTORICAL LINGUISTICS
http://www.cs.rice.edu/~nakhleh/CPHL/
M. Kelkar