In my experience, the original exec patched with exec44
works the best, and is great with OS3.9. I did encounter a few
programs that were troublesome with the BB2 exec, and also
IBrowse seemed to have some minor issues (believe it or
not, there was actually a site that would crash IBrowse *only*
when using the BB2 exec).
From my recollection there is NO advantage to using the newer exec
over the original patched with exec44.