I just remembered, they use a chip from AD, but I still don't remember which one, sorry.
According to this link
http://recforums.prosoundweb.com/index.php/m/194132/0/
they use SA5532AP.
Which might be true, I've seen them in my BLA Sparrow (alongside LM4562).
Anyway, in the case of the 2408Mk3 the result of the replacement of opamps and caps (also in the PSU section, used Panasonic FM/FC, Elma Cerafine) was less than overwhelming. A good external clock didn't do much either. I have modded other converters before where the results were much more obvious.
This doesn't mean that a mod with better results can't be done. From what I've heard the Black Lion mod improves the device quite a lot. At this point you pay for their experience, they invested a lot of time to find out what works best I guess and they probably wrecked more than one unit in the process.
So, if you plan on sending it off that's probably a better idea than doing the mod yourself (provided they adress PSU and clocking as well). On the other hand, from what I've heard a converter that is good out of the box still sounds better. I finally bought an Aurora to end my converter odyssey, which was a big step up from all the modded converters.