Which to use over BEHR semitransparent deck wood stain penetrating oil formula: TWP1500 or Defy Extreme?

1.Location: Central NJ
2.Deck gets morning sun for about four hours then is shaded by tall forest trees.
3.Wood is pressure treated fir in place about 22 years and previously power washed and stained professionally several times.
4.Last cleaning and staining was three years ago. Behr semi-transparent deck wood stain penetrating oil formula was used and the label states is cleaned up with soap and water.
5.The deck has developed large black areas and is dirty and the wood on the railing surfaces and floor boards is no longer smooth and flat but shows ridges and valleys.
6.The color is a reddish brown but my wife would now prefer a deeper brown perhaps in the tung oil color range which raises the following questions I would like to ask you.
a. I had seen the good remarks concerning the TWP1500 and the Defy Extreme and would like your recommendation on which to use over the Behr penetrating oil formula. I am confused since the Behr formula claims water clean up for an oil formula. Therefore in my mind I see difficulty if I were to us the Defy Extreme. I was considering the Defy Extreme after reading somewhere on this site that if water or moisture left in the wood from not drying out in my shady site would cause problems if an oil stain were used.
b. I am not troubled by the wood being uneven as a dark stain would make this less of problem for the over all look. I am just interested in getting a clean refreshed look and will consider in the future one of the composite decking materials.
c. Would it be better to stick with the same Behr product considering the chemistry involved?
d. From your experience can I get away with just power washing with wood cleaner or do you recommend going full out with the stain stripper and brightener route? Do you have favored products you could recommend?

As I will be doing this work myself, your recommendations would be very welcomed.