With regards to the color, I used white since IMO, it is the more accurate color than light bley, considering when you compare the color of the body with the clone's armor (like in this image), they look both white/dirty-white. And Hasbro models and even the LEGO one are colored white, so I guess the choice of the color white is the proper one since it has the approval of the Lucas license.
Onto the model, here’s what I think needs work:
Right now you have Z-74 handlebars on there, which aren’t accurate. They deliver the wrong shape and Minifig hand angle.
The handlebars stem from the area, brick building the sloping nose portion would render better results, and then you could leave a plate gap to attach the new handlebars onto. I agree on both points, I actually have an earlier version of a more accurate minifig handle bars placed on top of the brickbuilt sloping nose, but I ditched it since I liked this double steering vane set-up better.
The front-Right now you have those extra bulky 2x4 inverting pieces there. Using the white piece that you have on the underside on the back of your model(Which if removed will make the back more accurate, we’ll get to that later) And stick on the front it would slim down that portion. Then place a modified 1x1 brick with studs on 2 sides there to put jumper plates on for the thickening front portion.
Your repulsors are massive; compare the ones on the Salucami reference pic to a clones torso. Then hold the ski piece next to a lego minifigs torso –you’ll see what I mean. I know it's too wide, but for me it's the best looking set-up to approximate the shape and design, so I'm sticking with it for the moment unless there will be new pieces that would give that look at a slimmer width.
The Back- The use of the two 1x4 sloping white pieces side by side looks abnormally blocky, try putting 1 on there and using a modified 1x1 with studs on two sides to attach the correctly shaped plates on and capture the rounded back portion. This solution will also render a smoother transition to the 1x2 45 Grey brick, which is transitioned to abruptly. I actually revised the back portion already (because I also thought it was blocky), following a modified version of the 7913 model with 1 slope-wide and following Mr Man's suggestion of using cheese slopes for a more continuous slope transition (I will post photos tomorrow). However, I will no longer use the side plate approach that you employed in your model.
The width of the back is incredibly too high, 8 studs? I think 6 is pushing it. Try replacing that ski piece with a 1x2 tile, and reducing the Repulsor size. I also think it's too wide, brought about by the wideness of my side air intake design, which I will stick to. I might look at using 1x2 tiles at the back.
As you've seen, my approach is more focused on getting the more aesthetically-pleasing model even with some sacrifices in dimensional accuracy. Anyway, thanks for the criticism, I may or may not follow everything you said, but I appreciate hearing your side.