I am also in a bit of a dilema. About a year ago I bought a complete but loose Metroplex. It was in C9 conditions and its the one with Rubber wheels and Chrome.

Em I justified to buy a whole new one?? I already preordered an encore Omega when I already have a loose vintage one in excellent condition, I don't want to do the same with Metroplex.

I am also unsure if I should get the seekers or not. I have the Hasbro reissue of Skywarp and Cracker with the modified missiles. All that I need to do to make them 'good' is buy the loose missiles on ebay...So I don't know.
If I could get a minty original then that would be my preference. But you have to pay for a quality piece and ebay is hit and miss sometimes. Comparing vintage to reissues I've noticed that the moulding is softer (softer edges and lines) probably due to how old the moulds are, and the plastic looks inferior. Plus questionable QC in the current factories makes for an IMO inferior product.

With that all said though I'll still go for more encores because it's a just a lot easier to get a nice display piece without having to pay a fortune.