: When the wind is from the front advantage to feathered.
: When the wind is from the right side advantage to unfeathered.
: When the wind is from the left side advantage to unfeathered.
: When the wind is from the back advantage to unfeathered.

While this may strictly be true, the disadvantage of the feathered paddle in cross winds is minor. A low paddle stroke greatly reduces the blade exposure to the wind, and frankly any problem with cross winds really doesn't become noticeable until you are in winds of 30 knots or greater, and in winds like that there are really only two practical directions to paddle: upwind or downwind. Any progress across the wind is typically made at a significant ferry angle, so you end up paddling into the wind.

And paddling up wind in high winds, feathered paddles offer a significant advantage. You can generally start feeling the advantage at 15 to 20 knots, because paddle speed through the wind when paddling 4 kts is 23 to 28 kts (paddle speed = about 2 x boat speed) and the force of the wind increases at a square of the wind speed.

Likewise, any advantage of an unfeathered paddle while going down wind is minimal because the through-the-wind speed of the paddle is so much lower. With good conditions you can make 5 to 6 kts downwind so the paddle feels 3 to 10 kts of wind or less than 2% of the wind force you feel going upwind.

As a practical matter you spend much more time going upwind in strong winds where feathered has a distinct advantage. I have more than once spent several hours fighting upwind to a destination that only took 20 minutes to get back going downwind. I've done a lot of paddling in high winds over the years, and only very rarely have I noticed that the feathering caused an issue in side winds, and I soon forget about it, because those trips almost always turn into an upwind slog, with a short time of downwind mixed in.

Bottom line is the advantage of the feathered paddle in head winds is much greater than any advantage of unfeathered paddles might have when the wind is the other directions.

: Biomechanically less likely to cause repetitive stressd injury = unfeathered.
: Straight wrist push is physically stronger for the average paddler =
: unfeathered.

I always use a straight wrist. This is proper feathered paddle technique. With practice the amount of wrist motion is small even with a high feather angle. A 90 degree feather does not require 90 degrees of wrist motion. The wrist motion required is small, although learning the techniques takes practice.

: Easier to brace across another deck for rafting and/or standard rescues +
: unfeathered.

My 210 cm paddle is longer than two boats rafted together so the blades are not an issue, the blades hang out beyond the boats.

: Fits kayak deck contour better for standard paddle float reentry =
: unfeathered.

I'm not sure what how blade shape is effected by feathering, but the paddle float does not need the blade flat with the water in order to float.

: Off side blade clears kayak hull more easily during high sculling brace =
: unfeathered.
: Off side blade clears kayak hull more easily during roll = unfeathered.

Can't say that I have ever noticed the blade getting in the way bracing or rolling. I suppose it can happen, but with a little it shouldn't be an issue.

: Consistant blade position for faster braces on either side for average
: paddler = unfeathered.

I'm not sure how long it takes people to move their wrist a few degrees, but I think most people can do it in the time it takes them to raise one hand and lower the other.

: Years ago white water kayakers all used 90 degree feathers, now you can
: hardly find one and many have dropped to 75, the 60, now 45 and they will
: continue toward 30-20, etc as they see no advantage.

I don't see much advantage for whitewater paddlers, although winds do have a way of whipping up and down rivers.

: One advantage for WW paddlers using feathered was to clear racing gates
: better in competition, not for wind or bracing. The very top conditioned
: flat water racers can benefit from feathered even on calm days. Not the
: rest of us though.

I do not advocate people use feathered paddles if they are not comfortable with it. It does take some getting used to, but I disagree that they offer no benefit for the average paddler. It does not take much of a wind to have feathered paddle be easier going up wind. This advantage will be more noticeable for less conditioned paddlers who tire more quickly. One reason it may not be a significant advantage is they may well choose to stay home on those days where the wind is enough for it to make a difference.

Good feathered paddle technique takes practice, but so does good paddling technique in general. If someone just wants to go out for a nice relaxing paddle, they are probably not that interested in perfecting their technique or getting in good paddling shape, but as someone gets more dedicated to paddling, their technique will improve as will their physical conditioning and the range of conditions they may find enjoyable for paddling. Those people intent on doing more paddling should not dismiss the feathered paddle as worthless. It has advantages in many real kayaking conditions. Whether it is worth it for you will be a personal choice.