Rent isn't a big dance show...except for the big ballroom/Argentine tango number. And there's a lot of fast dancing in CCBB. So yes I'd say Joe's professional dance experience is just as extensive as Alexandra's.
The other thing that annoys me is the "poor Debbie's ballet training is as much handicap as advantage because the skills are so different she'll have to unlearn everything" when she was also a jobbing hoofer after she left Iran, picking up routines quickly in a variety of styles.
Mind you, judging from this video (not including TLDM) they weren't much cop. I reckon most celebs who'd made the quarter finals of Strictly would be in with a shot of a place.