After having some time to cool off... Shadow Lairs may be alright.

Take two deep breathes, then follow with me.
"Unique 5* materials guaranteed for each successful run"
This means every run guarantees you a piece of 5* gear as long as you're willing to alchemize the materials into armor. Now, let's do some math.
Let's assume you can buy a 2* piece of gear for 1.5k CR. The cost to get a 3* recipe is 4k CR, the cost to get a 4* recipe is 10k CR, and the cost to get a 5* recipe is 25k CR. Now, you also have to upgrade this item to 4* before you can do the 5* craft. This costs an additional 1k + 200 CE and 2.5k CR + 400 CE. All in all, this is going to cost you, if CE is worth 60 CR per, 1333 CE just to get an item ready to craft the 5* version.
This means that each shadow lair run is at minimum worth 1333 CE. This excludes whatever profit you gain from crowns.
This means even if you only get a shadow key in every five lockbock boxes, it can be worthwhile to run Shadow Lairs as long as you split the cost with a group. That is excluding whatever is contained within the lockboxes that could be sold. The value of accessorizes will no doubt go down, but any possible reimbursement helps make this a more worthwhile effort.
I would have preferred if it was easier to run Shadow Lairs, but this is what we have. You're able to do less runs, but each run is much more rewarding. It may actually save the bad players energy in the long run, as they'll have to do less trips reducing the number of potential deaths they'll face.

5 boxes = 3750 CE...
The prices of accessories have already crashed, their value has to go up, not down...
Lockboxes are 2k at the AH and still not selling...

I think what they meant by "Unique 5* materials guaranteed for each successful run" is that you get a material needed to upgrade an existing 4* armor into a new 5* Armor.
Like you need a Mod Calibrator material to craft a trinket, you might need a 5* Snarby's Paw material to craft the 5* Snarby armor using a 4* Ash Tail.
I don't think a single run gives you straight away a "unique already crafted 5* item" for each successful run, otherwise i don't see why there are special crafting machines after each ultimate dungeon...

5 boxes = 3750 CE.
3750 / 4 party members splitting the bill = 937.5
937.5 < 1333

Dont speculate until the release, you are guaranteed materials, but I havent read you are guaranteed enough materials for once. And we dont know the rarity of these keys, so we can't tell for sure how expensive a single run is. The new wording that a shadow key can be found on any lockbox would be cool if every lockbox had a key :P that way the market of lockboxes would go to key hunters, like I previously said on the other hand the accessory hunters could enjoy this if every lockbox contained an accessory, and a shadow key as well if lucky. Basically being guaranteed an accessory roll (or key roll) instead of one or the other. Are they able to cope otherwise? sure, but it's a kick in the balls.

You're talking about probabilities though. You're not guaranteed 1/5 or whatever odds they will have with their lockbox. You can open 20 and never get a key, as opposed to a lucky player next to you who gets 2 in a row. Give me a key for 1000 CE and I will attempt shadow lair, I won't if I have to spend more then that.

my issue isn't so much about the rarity but the lack of insurance for solo players that may want to use the key by themselves. what recourse do they have if they get disconnected or kicked for taking a long dump in the bathroom? better luck next time?

Sry but im not willing to gamble 750 CE for a slim chance at getting a key that only gives access ONCE to a place where I have no idea what to expect that may not to turn out to be worthwhile or too hard, chances are your not going to get a key with your first lockbox and you would have to find 3 other people who are willing to make that same gamble for 750 CE for your idea to work. Chances are getting the stuff you need for the new gear requires you to make multiple runs in the shadow lair, would you be willing to do the silver key gamble again?
http://forums.spiralknights.com/en/node/29859?page=1
Post #99
No way to confirm if that is true or not, but if it is the hopes for even a 1/5 chance may be way too optimistic

um there's like 5 shadow keys on AH already :/

"I don't think a single run gives you straight away a "unique already crafted 5* item" for each successful run, otherwise i don't see why there are special crafting machines after each ultimate dungeon..."
Right. This is why I didn't factor that extra 800 CE + 5k CR. If it gave straight away 5* items, this would definitely be profitable.

why not do royal jelly runs and such in proto gear? :D think it will come close to otherwise paying an inhuman ammount of CE to MAYBE play the real thing hahaha

The big(gest) problem I see right now is the (apparent) rarity of the keys. I have watched multiple Knight use dozens of boxes (one almost hit 30 boxes) without any key at all. This suggests they are nearly as rare as some of the more expensive accessories. There are nearly 10 Shadow Key auctions in the AH right now (none with buyouts), all with bids around 50k at the moment. I'm guessing they will go well over 100k, maybe even upwards of 200k within the next 2 days. That's just a guess, though, assuming they remain as seemingly rare as they are now.
I'm sure these runs will pay off, in their own way, assuming the players who do them are skilled enough to complete the levels. It's just a matter of how much one is willing to spend virtually, much like accessories themselves.
Though, in all honesty, I still feel like this whole thing is a bit of a slap in the face. :(

I know two people who opened over 60 boxes each
The average key rate so far is about 1/30

"I know two people who opened over 60 boxes each
The average key rate so far is about 1/30
"
Admittedly from what I've heard so far the profit potential grows smaller and smaller. HOWEVER, if it is possible to get more than one of these unique materials in a single run, then the profitably of these runs is still up for discussion. All we know is that we get AT LEAST one.

Waw, assuming the average rate is 1/30.
Does that mean the average CE to spend on lockboxes to get one key is: 750 CE * 30 ?
and those two guys might just be lucky.
Interesting theory, would be good if the numbers work out similarly.