I have tried the black layered (don't think it's the dye color!) Hi-Space Carbon as well.
On three recorders (LG, LiteOn and Plextor).
On all of them, the results were far from "best of breed" (I.e. TY/MCC/Ricoh).
However, some magazines in Germany have claimed superior UV resistance for these discs. This remains to be proven IMHO, but sounds very plausible.
However, on a general note about longevity/storage, I'd look at the following issues:
- stability of the dye (one usually only has mfg propaganda on this, but it's better than nothing)
- manufacturing process quality (does manufacturer have "bad batches" every now and then? Do they have a long history of spotty quality? Or are they mostly known for superior quality like TY is?)
- label layer protection (esp. if you handle the discs a lot and not just store them). Additional scratch protection or lamination on the label layer can improve protection of the data, without severely affecting the initial burn quality
- media stress and/or longevity tests done by trusted 3rd parties (don't trust manufacturer "longevity equations", just the dye stability analysis as a rough indicator)
- reflective layer materials (this can be really tricky, because not only the materials, but the bonding affect corrosion and some manufacturers claim to be using "gold" when in fact they are using a mixture of something that can in practise be worse than aluminium)
- price of the discs (high price doesn't always equate better quality, but among the bests discs it may have some value)
- higher grade usage (i.e. medical grade discs for storage, etc)
Based on these factors I wouldn't be so interested in any "black discs", just because they are black.
However, if they were TY made blacks with good label side lamination, I had tested/burned a few batches and seen low level measurements from them, then why not? One issue to consider is that the black ones do have lower levels of reflectivity.
If you want most reliable optical cd/dvd storage money can buy you, then buy the medical grade discs (e.g. TDK).
Even if they fail, at least you can sue the hell out of TDK, because they charged you an arm and a leg for the discs and promised they would last 100 years :)