I've been away for awhile, so I hope this is still relevant. I've been using Scrivener for just over a year (it was recommended to me by a church friend who writes science fiction). It is a brilliant piece of software. I use the Windows version, and while there are a few things that the Mac version can do that haven't been ported to the Windows version yet, I haven't run into them. I think they're mostly fairly marginal.
I just tried dragging some BW notes files in .rtf format into Scrivener, and they came across perfectly. They are pretty simple files, but I suppose most notes files would be. Be aware that what happens when you do this is that Scrivener creates a copy of the file within its own folder structure, which it keeps track of through an internal indexing system. If you edit the file in Scrivener, your edits are not saved back to the BW notes file; you have to do that manually. This bothered me a bit at first, but Scrivener does so much else so well that I no longer mind; and I've come to understand the reasons that it works this way.
When writing a sermon these days, I'll do textual research in BW, then sometimes copy verses or passages into a Scrivener file. I organize my thoughts and draft paragraphs or more in Scrivener. Then I copy these over into Nota Bene for the actual final writing. I could also export them from Scrivener as RTF and import into NB.
Scrivener is an amazing organizational tool. It easily handles copying and pasting of Hebrew and Greek from BW (see the screenshot), and you can import images, Web pages, documents, etc. It's become an integral part of my research and writing process, and I recommend it. It was originally designed for fiction writers (and no preacher wants to be known as that, eh? ), but it is so flexible that you can use the parts of it you need in the way you want for whatever writing you're doing.
But, as others have said, it's not intended to be a full-featured word processor (though, interestingly, it is capable of publishing ebooks). For final formatting and tweaking of sophisticated documents, it's recommended that one export to a word processor.
And on that subject, Don, if you're shopping I hope you'll at least take a look at Nota Bene. It runs on Mac under either Parallels or WINE; I haven't used it on a Mac, but many report success. NB was created by a scholar for scholars, and its handling of multiple languages, standard word-processing tasks (want to transpose two words or two sentences with a single keystroke?), research databases, footnotes, and bibliographies is well above what Word can do, since Word's user base is a different one. NB is currently in the final pre-release stage of v. 10. I've been active in the beta testing, and I can say that the latest beta is essentially ready to use.