I came to the same conclusion and purchased BusyCal yesterday. (Was able to get a discount of $9.80 with the code: SCREENCASTS )
I did ask BusyCal how to import a NowX calendar and they said "the AppleScript only converts NUD, not NOW X. Supposedly Now X already syncs with iCal. I'm not sure how smile but perhaps there is something on some of the Now Software support forums that talks about it." So, here I am!

I would really appreciate a "how to" for importing NowX to BusyCal. Too bad THEY don't know how to do it! Thank you!