We'd like to get the 3.5 version out simply because of the work that has already been invested in it. With regard to 4th edition, I doubt we'll get an early look at the rules before they are published or indeed the Open Gaming Content prior to its release, so we would still have a scramble to convert over.
My earlier comment was based on the assumption that you wouldn't get an early look at either 4th ed or the OGL, but that the similarities between 3.5 and 4th would allow a relatively easy conversion. Admittedly, my assumption that 3.5 and 4th won't be that different is based solely on information that I have picked up on the net, so it may be totally erroneous
Of course, the other factor that I have no knowledge of is how much time you have to devote to this project, which could well have a serious effect on the timeframe.
However, if you release the 3.5 version, and 4th ed turns out to be sufficiently different as to make conversion a non-trivial exercise, I would have thought you then run the risk and having sales pretty much completely dry up as players convert to 4th ed, except of course, for the SW faithful. And as one of them
, I eagerly await the chance to buy any new SW product.
Hawk