The one question that remains is how this game compares to a card game with a ever shifting 'metagame'. With a game like Game of Thrones lcg, you had to keep up with the latest expansions to be able to play and the earlier expansions became obsolete. I'm a collector at heart and would love to buy all expansions for X-Wing as well, just hate to buy the first ones only to realise they were essentially worthless since the 'metagame' had already moved away from those kinds of ships.
There is a shifting meta, but it's quite different to an LCG. In terms of the current top-tier ships I'd say there are 4 at the moment: TIE fighter, Millenium Falcon, B-wing, TIE Phantom. Respectively that is one ship from each of wave 1, 2, 3, and 4; so its not simply that the newest is best. Also, there is a much narrower spread of effectiveness than in an LCG, I don't think there are any ships in X-wing that are unplayable but there are lots of cards in AGOT which you would never put in a deck.
Put it this way, if I were to start buying now I'd still buy everything I have currently; there's nothing I would avoid buying due to it having been outclassed. The only ship I have which has never seen the table is the Falcon, and that's just because I don't really like it; it's probably the best ship in the game currently.