I don't think it is unrealistic to cover the faded redwood stain with a semi-transparent dark brown. I don' disagree with Steve, but if the wood is in good overall condition, I don't think you want to go to a solid color stain yet. Personally, I see no difference between solid stain and a deck and floor paint. I think I would perhaps sand the deck or at least powerwash. That should remove most of the old color. Sanding can make any deck look absolutely new. The Olympic prodicts (PPG) are very good quality and their Maximum tinted product is an alkalyd oil that should give you the color and performance you are looking for. 3-years is good performance. Since you still have wood worth refinishing, stick with a winner.