Hi jeremyclarke. Welcome, and thank you for the compliments.
Your concerns are not only legitimate, but fundamental for the success of this project.
If what you want is barely activeCollab but 100%, maybe ProjectPier is the project for you. We are already in touch, and hopefully both projects will work together. I didn't contribute much this past week since I am visiting California. It's just too much work (and fun) here. That leaves little time.
What we want to do with OpenGoo is a bit more ambitious, mashing together many Open Source apps, to get greater functionality (the "Web Office").
So one goal of OpenGoo, as a framework, is to have the ability to decide which featrues (apps) you will use. For example, for text editing, maybe you would like to use TinyMCE as the text editor, instead of FCKEditor, a full or a light version, a wiki engine, etc. The framework should let you make the choice (like linux packages).
Another goal is simplicity of the UI. I myself love wikis (dokuwiki in particular), and I find that I can document almost anything in one of those things. But wikis, as easy as they may seem to some, are way too difficult for most. That is why the UI should stay as clean as possible (as Google teaches us).
Since the system will usually run on a server, you shouldn't be concerned about performance (unless you plan on installing it on a 386 with 64MB RAM, which I wouldn't recommend). You won't need large chunks of memory on your client PC. That's the beauty of the AJAX Web (Web 2.0).