The only time I saw the Enterprise A with a yellowish deflector dish was when she was in dry dock in TMP, and shortly afterwords as she was leaving the Sol System. So IMO, it wouldn't really be cannon to see the Refit Constitution with the deflector being yellow all the time, save for warp. Because we see the Constitution with a blue deflector at both high and low impulse throughout the entire series, do we not? I'm not going to discredit this entirely though, as it is an interesting idea, but personally, the only time I see the deflector being at low power is in drydock, when the ship would depend on the station's deflector grid, anyways. Again, just IMO. Personal preference and all that.
Nevertheless, this ship is looking rather hot. I've been seeing a lot of connies and connie related starships recently, and it's nice to see the old girl out and about again. I look forward to seeing what you cook up later on. Keep up the good work.
-Aeries.