>I am being criticized with arguments that are in reality in favour of what
>I wrote.
I am not trying to criticize, but to think with you, offering both support
and challenge. That is why I suggest alternatives to your weaker -ss-
forms.
>In a given period /Vgt/ becomes /V:kt/, while /Vkt/ is unchanged;
We cannot push the change back earlier than the separation of Umbrian from
Latin (because it is not found in Umbrian - there is evidence, as I quoted
earlier); and we cannot suggest that
*/Vgt/ survived as late as that. Your suggestion that ago ~ *actus was
"recast" as ago ~ *ag+tos, while facio ~ factus was "recast" as
facio ~ fac+tos (and this "recasting" later lengthened the vowel in words
with a final voiced root) avoids this.
The "analogy with the vowel length of the perfect" idea also explains all
this, with only a few exceptions - and your theory is not yet without
exceptions.
Peter