The answer from Justin ist perfect, couldn't have say it better :-)
All the product you are comparing, you need to think also to another thing.
Structured and Non-Structured Data.
CMOD can do only Structured data, and he's good at it, so good that he's number one.
FileNet, Documentum, LiveLink, SharePoint, .... are more players in the Non-Structured data field.
Of course, FileNet, Documentum, etc can/could do also Structured Data archiving, but they are nowhere as good as CMOD.
Simply put, it's another field, another rules.
Each tools has his good side and bad side.
CMOD is really easy and has excellent performance in its own field, meaning cold archiving.
Yes the others can do that too, but not at the performance level of CMOD.
It follows the philosophy, do one thing, but do it well.
If you take FileNet, it's a neat and nice product, but the installation is a nightmare, the fixes are less than optimal like CMOD.
Well it's a wonderfull product on its field, for all unstructured data, BPM, etc... it's number one, or nearly at the top (I'm not sure at which ranks)
But for doing the work of CMOD, it's overkill.
That's why you have now the integration with CMOD, so you can the best of both world.
At least at IBM, we don't see them as competitors, but as complementary products, which can give to the customer the best option on each field.
You know the whole idea of having one system which is number 1 in everything and with performance... is a dream.
Cheers,
Alessandro