I posted on this stuff awhile back, and the only thing I'm concerned about is the dimensional factor (ie, is there any original set footage actually shot on widescreen)? I don't want to see croppings like they did in TATV (the replicator).
Of course once they start it is going to take a lot longer than TOS will. Just due to significantly larger number of episodes TNG has. The price will be higher too. I wonder if they would take the same approach in terms of the order of the episodes. Working on the favorites first.
One advantage this would have is many of the people who did the effects and editing on TNG are still around to consult.
What about those old TNN/Spike marathons? As you said, the favourites can be worked upon months in advance, and then aired.
[This coming from a guy who doesn't own any TNG video at home.
Here's one new effect I hereby suggest: what about CGI shots of the Ent-D's MAIN shuttlebay? [Probably better, then, to replace those mediocre shots in "Cause and Effect," as realistic as those shots were when compared to ILM's outdated work.]