I don't think they should use previous contestants. Alesha Dixon on SCD proved what a bad idea that was, although Bonnie Langford, with her wealth of experience and expertise as a dancer, would probably be accepted by most viewers. I'm not sure that Kyran would be accepted and Suzanne Shaw probably won't have time now because of her commitments on Emmerdale.
Alternatively, Anita Harris, who's an actress, singer, very good dancer and accomplished skater would be good. She has the skating knowledge plus she has the performance background that the producers seem to want. The problem with her is that she hasn't done much TV work in quite a while, so a lot of viewers wouldn't know who she is.
I also think that now that she's left SCD and is working on GMTV, thus making her an ITV person, perhaps Camilla Dallerup would be good. As a former pro dancer on SCD, she also has a wealth of experience and expertise as a dancer and she knows what it's like to train with novices for a show like this.
Personally, I think they should keep the five judges but they should make a point of rotating more between who's asked to speak instead of focusing primarily on Jason. People are getting fed up with him because he's being asked to comment so much out of proportion to everyone else. (Less is more, ITV, less is more! It is possible to have too much of a good thing.) Otherwise, if they cut it down to three judges, I'd like it to be Jason, Karen and Robin. I know Jason went too far on Sunday but he's not usually that bad and I rather think he's probably learned his lesson due to the fallout. Karen and Jason balance each other perfectly, with Karen being the nice judge and Jason being the nasty one. And Robin is the voice of reason in between. Nicky's too erratic for me.