Point out to me where I've insulted you in any way, and I'll sincerely apologise.
I think I insulted the caliber of your opponents twice, but not you!
Oh, and I also rather thoroughly panned Dark Reapers, but I hope you won't take that personally.
Looks lets take a step and see what the original question was. Are Crimson Hunters competitive? My answer is "Maybe"
(the Wraith Flyers are clearly not)
IF you spend points to baby them, IF you counter the normal threats, then yes. They will own the skys and only ON OCCASION get shot down by rapid firing Tau. For example a Hunter Exarch (which you should never take) is great at killing enemy MC's with some Star Cannons.
IF you don't spend the points required to fit them into your lists they will literately crash and burn, in this case the "points required" vary from list to list and player to player.
If you are going to spend 300 points on a Wraithknight, then you can 300 spend points on a 8 man Reaper unit with Krakk upgrades instead. Nothing else in the Eldar codex can handle the wide variety of threats that an Eldar player faces on average these days. While the new Nid book is not exactly a power house I remind you 9-11 Krakk missiles (hopefully with Twin Link and Monster Hunter) is excellent in taking out a three man Fex unit, AND can kill opposing Wraithknights quickly etc etc.
While you don't seem to like the idea of taking Tau as allys, especially if the Commander is just providing buffs...like a farseer, you cannot deny the reliability of Ignore Cover and such. In this situation you don't HAVE to take one, but when you fight against someone who does and they wipe unit after unit without providing a save its going to feel frustrating.
As my signature clearly suggests "The Eldar, more than any other army, should not only look at the output of each unit individually, but the synergy of multiple units together and their role in the force as a whole. - Fable"
Taking one or two Reapers units can be expensive and they CAN die easily, when you throw the weight of the remaining army behind it however then everything, even Shinning Spears, shine.
I also HIGHLY recommend taking some sort of defensive fortification, in this specific case of Crimson Hunters, Void Shields will protect your flyers if you but fly them in the bubble. For a measly 100 points (the cost of a Defense Line+Quad) you are stopping all but the most dedicated AA options. If you are feeling frisky you can pump even more points and basically make them (and everything else under the shields) immune to ranged firepower.
While you very clearly do not have to take Reapers, IF you are taking Crimson Hunters and want to make the most of them, I highly recommend
taking at least one unit of them to make them Competitive. Otherwise (as you pointed out) without some favorable terrain its going to be rough keeping them alive.