open baffle vs sealed box designs

OB need a separate low freq channel -- and it's usually a closed box. OR you need sophisticated equalisation (as in Linkwitz's Orion).

BTW, I love the OB sound.
So, I really don't think you'll be UNhappy with either the fostex (above-never heard them) or the Bastanis (heard these).
If you're good at electronics you might have a go at the Orions (here). This speaker is world class (IMO, etc).

Not sure what OP meant by open baffle vs sealed box, but the purpose of the baffle is to avoid cancellation of front and rear propagations from a speaker, so at low frequencies (long wave lengths) the baffle has to be quite large. Thus you expect the LF section to be a more or less sealed box of some type. Not sure what the value for HF is purported to be, or why one wold expect such an arrangement to have value.

db

One other design that has recently surfaced is from Germany and costs about $475.00- $500.00/speaker plus shipping. It's called the NoBox BB. I cannot comment on the sound but Dick Olsher did a review at EnjoyTheMusic.com.
One other thing, as with any kit speaker, you have to build the baffle (or get someone to build it for you). Plans are on the web site.

You could get the Fertin 20EX. They're great in an open
baffle. You get stunning clarity and speed and surprising
bass. You'll pay a bit more. The baffles are easy to
build and not expensive at all. You could e-mail me and I
can send you the plan.