Does that make sense? Can we agree on those last two points?
I can agree to both of those points.
I'm just trying to get away from the general 'they are fine, you just have to play them correctly' attitude that I see in may places. I fear that when their time for a rework comes a vocal group will say they are fine as is and that will end that discussion.
I want to like them, they could be quite interesting, but they are so weak for their points that they seem like an anchor in any list i field them in.
I feel like ma y others have said in that claiming that destors are "fine" is just the wrong way to go. They are anything but "fine" they are a nitch model, that you badically have to 100% build your list around, to work in a few very specific types of cases.
First assault. Those supporting them basically say ignore this rule, which is where a bit of their costs come from. This is where the skornegy is an issue. This ablity isn't functional as is. It either needs a change to how it works or replaced to help justify the cost. The one situation you mentioned maybe using it was against heavies, however they will have a hard time doing much to heavies. Angaist armor 18 they need at least average rolls to do damage, and higher armored enemies are fairly common. Those higher armored thints however will rarely be troubled by armor 17 with 4 boxes.
Destors are not really that much better on armor than sentinels. Sents are base 15, but get +2 arm when base to base sonething easy to achieve. Add to this the destors 4 boxes mean each model is harder to remove, but the unit itself not much with half the number of models total. This also means that those 5 models need to get a lot of work done every turn to match the number of attacks the sentinels could a turn. Considering that if you lose only one sentinel, it is posible for them to get 18+ attacks a turn this isn't easy. Let alone the sentinals UA is very good and while the thane is much less so for 3 more points than the UA.
Your mention of good against e-leaps is interesting to me, because while they likely can survive a few more eleaps, they will struggle against the models in that list. Storm striders, thunderhead, hurricanes, stormclads, etc are all fairly common in e-leap list and all have high armour and other ways of removing destors easily. Heck the main shot off a stoem strider is a pow 15 and if a firefly is close it will be pow 17, more than enough to likely kill a destor and perfect to start a chain of leaps. This is a case where compairing themes is ideal, and against eleaps in general you are better off taking something like forges, with a lot of jacks, than any kind of infantry heavy list. Destors are ok if for some reason you have to bring dawnguard, but this is not what they are designed to deal with.