Well, if you ask me, and you haven't

, I think it's best to stick with the classic design for now, until such time as it's determined that the five year mission is finally concluded (a live action version of
"The Doctor and the Enterprise" is an idea worth considering; I might even work up a screenplay).
Then, after a brief hiatus for retooling,
really start off with Phase II as originally intended, to depict the second five year mission.
Now, something to take into account with this approach is whether to pick up where TMP left off, since it's set only a few years after the end of initial five year mission, or, at this stage, say to hell with the established timeline from this point forward and start plowing some new ground.
If you decided to stick with the established timeline, there's a matter of how much of the TMP designs to stick with and for how long. The ship is pretty much set in stone, thanks to the subsequent movies, but there's nothing to say that the gray pajama uniforms went over about as well with the personnel as they did with the fans (like the proverbial lead balloon), and Starfleet went back to the TOS styles for a time, maybe with the addition of the medical scanning belt buckles, wrist communicators, and upgraded phasers, eventually transitioning to the TWOK uniforms.
It's an idea...
As for Dochterman's Phase II E rendering, I think the most off-putting aspect was that there was a little too much TMP in there. The original idea was that the saucer would be largely unchanged; it was the secondary hull and nacelles that would be swapped out with higher powered versions.
I think something along these lines might've gone over better...