Got some good stuff here, guys, especially if you could get the action simultaneous, but it is making the movie longer. The 2nd half of act 2 is always way too slow in all versions of TMP, so maybe the thing to do is go back to IN THY IMAGE, where they discover vger is derived from a NASA probe much earlier, so it isn't THE BIG (notsobig) revelation, but instead a major plot turn. That would cut down a lot of gawking and slow stuff in act 3.
The Kirk/Decker division of labor is an echo of Wise's ANDROMEDA STRAIN, where the titular hero played by Arthur Hill basically just is in charge and survives, while the younger action hero played by James Olson is the guy who actually has to do climbing and get shot by lasers. There's even something of this in Wise's HINDENBURG if you want to think of William Atherton's well-meaning antagonist as the action guy of the piece against George Scott's grand old disillusioned german.
I just saw Wise's Andormeda Strain a couple weeks back. Great movie...and yes, I see your point.
The movie, TMP, would have to have been rewritten. When the 'energy' probe comes aboard, I would have had it enter Ilya's body on the bridge right there and then, possessing her right away. Though, at times, the real Ilya is able to get 'through' the influence of the probe.
She tells them what has to happen..and they have to get to the center of the cloud. Vger is weakinging (for whatever reason). They eventually go to the transporter to beam down but Vger only allows Decker/Ilya to just as the klingon ship attacks the enterprise.
While Kirk deals with the Klingons, they also are in contact with Decker. We see Decker come upon Vger and Kirk, and spock, see that it is a voyager probe. That is when Ilya says that VGR must join with the creator. They all realize what it means, Kirk says he will come down and do it. Spock reminds Kirk they are in battle the Klingons, there is no way he can beam down with lower the shields.
Then Decker does it, joins with Vgr. And then we find out that the Klingon ship was really an illusion created by VGR to get Decker away from them...
The end.
Rob