Really depends on what you are trying to do with the video. If you need mkv or mp4, then Ripbot is a perfectly valid choice for re-encoding the blu ray video and making smaller sized files. If you are doing a backup and want to burn to a blank 25gb blu ray disk, or save on a hard drive as blu ray format in a smaller size than the original, then BD Rebuilder is what I would use.
I haven’t heard of that converter you mentioned…so can’t comment on it.
DVDFab has a Blu ray to Blu ray module available now. It is supposed to be fairly fast, though you can set up BD Rebuilder to match it in speed if you don’t want 2 pass encoding.
The separate hard drive trick is only a minor speed saving. As MrPete shows us, a modern cpu/system is far more important. I’m using a Core2 Duo quad core machine (9550) and I can reencode with BD Rebuilder in about 8 hrs for most blu ray movies, doing movie only backups.