activeCollab and eGroupWare aren't even in the same class of applications, so a direct comparison is kind of silly. aC is for project management while eGW is "groupware", which my corpspeak-to-English translator defines as "software management uses to pretend they're getting stuff done", as opposed to software that actually helps get stuff done.
Seriously though, I'm having trouble figuring out exactly what eGW does. Ok, so it's "groupware", which I think means some sort of Microsoft Exchange-type calendar/address book/e-mail type of thing. It doesn't sound anything like aC, and their web site isn't very helpful about explaining it. In any case, it's a much more complicated application than aC and seems to attempt to solve different problems entirely.
activeCollab is new, but by nearly all reports it's a very well designed (backend as well as interface), usable application. It mainly seems to appeal to the people who can't or don't want to use a third-party service like Basecamp. If I were to hazard a guess, I'd say that someone at DH probably falls into this group and so wants to support aC development and adoption.
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