It's known that the original Pyro's ie with the hero/nice paintjobs as seen on the table top pix were used in the initial shots. Lucas later decided they needed to be more spectacular and called in a pyrotechnic expert to complete the shots. For those they used more dare I say badly or hurriedly painted models. You can see an example of this in the Japanese magazine shot with a dodgy looking red 4 pyro leaning against a shelf or something. Also note that the "triangles" y was rigged as a pyro model and blown to smithers.
I just got done watching the 2006 theatrical DVD and BluRay battle scenes back to back, with judicious pausing. I can't believe how well the original model tracking shots hold, and how much more convincing the models are when compared to the CGI model (which seems more animated).
I heard about there being two sets of pyro shots being done, because Lucas wanted a fireball explosion (plasma explosion?) and was not satisfied with the initial attempts. Now those first attempts might have consumed the "nice" pyros and they built new "rough" pyros for the second 'splosions, or did they always have "rough" pyros for the intial and second explosions? As far as I can tell, those "nice" pyros had armatures in them and may have had the engine lights too. The true pyros should have been plastic shells and pre-scored to break apart. The existence of Red Leader and Red 2 "nice" pyros doesn't make sense either, as neither of those ships exploded on screen. They were both hit by green blaster fire, but the damage to the ships was an optical effect, Red 2 got away and Red Leader's crash is a charge going off on the Death Star surface with no ship present. When I was just watching the scenes, I was taking note of the pyros and I could not see markings on the ships, but Red 6 had some stick guns when going up, Red 4 was its own explosion, Red 12 went up with whatever ship stood in for Red 10 composted next to it, and Red 5's explosion was a repeat of Red 10's. So there were 4 pyro X-Wings that got blow'd up good that made it to the final cut. All of them sweet fireballs. I could not make out a Red 6 or Red 12 "nice" pyro model (I'll keep looking), but when Red 4 is being chased by the TIE, you can see the bottom of his ship and I count 4 stripes on it. Next time I'm going to watch it with my computer in front of me with reference pics up and see if I can spot the "nice" pyros from the heros (I swear several of the Red 5 shots look like a "nice" pyro). I know in the two shots of X-wings leaving the moon and approaching the Death Star they are hero versions because their wings are closed. The the four ships heading toward the Death Star when the lock S-foils are definitely heros. But I'm wondering if the ships with exhaust lights are only heros, or if there were "nice" pyros equipped with engine lights too? If not, that certainly limits the scenes of any "nice" pyros to front or side shots.
After reviewing the Y-wing threads some more, I realized I reversed the MOM model and the blue/gray model. From what I've read, the MOM tour model is a pyro that survived ANH and was detailed for use in ESB. The blue/gray apparently is Tiree's ship, and I can definitely see it flying next to Gold Leader in his cockpit shots and then again when flying at the camera in the trench and from the side. The extra yellow panel on the front left side and the missing yellow stripes on the engines are a clear indicator. Unfortunately the TIE Killer has some weathering on the engine domes around the same area that the triangles are on the other ship, which makes it hard to tell them apart in fast moving shots. I see the TIE Killer has a gray canopy, so I'm going to watch for that next time in the trench. But I do see that when Gold Leader is in his cockpit getting ready for his run, the two ships outside are the blue/gray and the TIE Killer, ooops! Maybe Pops flies the TIE Killer instead? The surviving Y-Wing has marks on the engines when it is leaving the Death Star, but it is not clear if it is the triangles or TIE Killer ship (I guess it might be a force ghost of the ship, the other ships appear to be Red Leader and Red 3 too). The three pyrotechnics of the Y-Wings appear to be different shots or 3 separate pyros. All three Y-Wings when viewed from the back have engine lights, but I noticed a few of the Y-Wing shots are reuses.
I might have to try cutting the model shots together for a YouTube video for analysis sometime down the line.
I assume the sunglasses were to provide scale. 
