Bongos3 is a new version and unfortunately the settings in Bongos 2 will not copy to 3. Bongos2 will still work with 2.4 but the author is discontinuing its support in favor of 3 within the next month and has no intention as of today of making any sort of profile copy feature =/
Just an FYI.
Just to let you know, changing over from Bongos2 to 3 actually doesnt take very long to do. I was able to set everything up in <5 min per character. I made a movie on how to do the basics for first time configuration which im uploading now. If you intend to swap to Bongos3, dont do ANYTHING until you watch this movie to configure it if you want your old basic bar settings to copy over.
You will still need to size and position the bars, but the icons should all remain in the same spaces if you follow the video instructions.
You can find a list of commands and other information on the Wiki page for Bongos3 here:
http://www.wowwiki.com/Bongos3 (http://www.wowwiki.com/Bongos3)