Well, for somebody who's not a bass player, you certainly have damn fine taste in bass gear!!!! You really can't go wrong with any gear that says either Eden or Avalon on it.
As for whether or not the DI on the Eden head is "just as good" as the Avalon DI, that's hard to answer, since you are really comparing apples to oranges. Both are world class items, but they will sound very different. The Avalon is relatively neutral, tonally-speaking, whereas the output from the Eden will have the tonal characteristics of the Eden head. (I would describe it as having a very "boutique bass sound" but with a nice bump in the midrange.) If this sound works for you, then I suppose you really wouldn't need the Avalon. But if you can swing for both, you'd have a nice variety of bass tones. Plus, you'd end up using the Avalon for other instruments as well.
Since you've obviously already found a dealer who handles the Eden line, you might also check into their "Nemesis" line. A little cheaper and a lot lighter to carry. Very similar in tone.
Either way, I think you'll definitely be happy with either or both of those items. ROCK ON, MAN!!!!
As for basses, I don't even know where to start making recommendations for that. There are just soooo many nice basses out these days. Maybe a Warwick? Just play a lot of 'em and pick the one that floats your boat.
