It seems clearly that there is some relationship between the Vision of Isaiah and statements made in the Pauline letters. I don't claim to understand the relationship. It seems to me, however, that Vision of Isaiah is a better expression of the account of Jesus that Paul knew. If we ask, "Who was the Jesus that Paul was preaching?" It seems that we find a figure much closer to the one that Paul was preaching in Vision of Isaiah than what we find in any of the canonical Gospels.
Key passages that indicate Paul's concept of Jesus, taken from BeDuhn's reconstruction of Marcion's Pauline letters:
6 Now we speak wisdom among those who are
perfect, [but not the wisdom of this aeon nor that] of the
rulers of this aeon, who are being nullified. 7 [But] we
speak God’s hidden wisdom in an initiation, which God
premeditated before the aeons for our glory, 8 which none
of the rulers of this aeon knew; for if they had known,
they would never have staked the glorious Master. . . .
16 For “who knew (the) Master’s mind, and who became
its counselor?”
(Note that 1 Cor 2:16 cites Isaiah 40:13)
1 Now I remind you, (my) colleagues, the proclamation
that I proclaimed to you. . . . 3. . . that Christos
died . . . 4 and [that he] was entombed, and [that he] has
been awoken on the third day . . . 11. . . so we declare and
so you believed. 12 [Now . . . how is it that] some among
you say there is no awakening of (the) dead? 13 If (the) dead
are not awoken, neither has Christos been awoken. 14 And
if Christos has not been awoken, our declaration (is) useless.
. . . 21 [For] since death is through a human being,
awakening [of the dead] is also through a human being.
22 [For] just as in Adam all die, so also in the Christos all
will be made alive. . . . 25 For it is necessary that he rule
until he has put (his) enemies under his feet, 26 [death
(being) the last enemy to be abolished. . . . 29 Otherwise,]
what will they do who are being washed as surrogates for
the dead?
“The first human being, Adam, became a living
soul.” The last Master (became) a life-giving spirit. 46 The
spiritual is not first, [but that which is animate (is first), afterward
(comes) that which is spiritual.] 47 The first human
being is from the earth, soily; the second is the Master from
(the) celestial sphere. 48 As the soily one is, so also (are) the
soily ones; and as the supercelestial one is, so also (are)
the supercelestial ones. 49 Just as we have borne the image
of the soily one, we should bear also the image of the
supercelestial one.
. . . 5 [Think this about yourselves (what you think)
also about] Christos Jesus, 6who, although he existed in
God’s form, did not consider a seizure of equality to God,
7 but emptied himself, taking a slave’s form, becoming in
the likeness of a human being; 8 and being found in an appearance
as a human being, [he humbled himself and became]
obedient as far as death, even a death by staking
Using BeDuhn is not ideal, but I do have concern about proto-orthodox corruption of the letters in ways that obscure our understanding of what "Paul" was preaching, so using BeDuhn is just a relatively convenient (and admittedly flawed) way to to work around that. It's not perfect, but I think it helps.
We can compare these statements from Paul to what we find in Vision of Isaiah:
So, the Pauline letters tell us that:
1) The rulers of the world did not recognize Christ and they would not have crucified him if they had recognized him.
2) He was buried and rose after three days.
3) His mission was to defeat death.*
4) He came from heaven.
5) He was transfigured into the appearance of a human being.
* We can note that the statement about abolishing death in 1 Cor 15 implies that death will be abolished during his rule in heaven, not that he abolished it when he descended into the underworld.
Likewise the Vision of Isaiah says that:
1) Christ will be crucified by the price of this world while he does not recognize him.
2) Having been killed, he will descend into "hell" where he will defeat the prince of death.
3) He will rise after three days.
4) Christ will descend from heaven...
5) Being transfigured into the form of the inhabitants of each level of heaven, until finally reaching the earth and taking on the form of a man.
It seems to me that we cannot find the Jesus of the Gospels in the Pauline letters, but we can find the Christ of of Vision of Isaiah there. This would seem to support the view that at least some layer of Vision of Isaiah predates any canonical Gospel, and constitutes a version of the Jesus narrative that would have been familiar to perhaps the original writer of the Pauline letters.
So... now what???