I have the same Omega Plant Ocean, although Ive just got the black bezel fitted, as I fed up with the orange look(I strongly recommend doing this). I looked at buying a Rolex Milgaus recently, so I know what the Planet Ocean is worth - approx £800 -£1000 as a trade in and £1500 or so via fleabay.
After swapping the bezel I have decided to keep it! Definatley looks smarter than the TAG, so if it were me I'd sell the TAG.
I also have a TAG, but a 2000 Aquaracer ( I think thats the model), its as strong as an ox.