Surprise, surprise.
To be honest I have never been a big fan of Camo, but he seems to have upped his game during Capello's reign.

. But there are two reason why I would prefer to see Mancini than Camo.
Firstly, and the main reason is financial. I am not just sold on Barzagli such an exorbiant price. I am big fan of him, but right now, there are cheaper alternatives available. Metzelder on a free, and I am sure we can talk ManUre out of Heinze via loan with an option to buy at the end of season. In any case, Samuel is somewhat unknown quantity at this stage, but I always prefer a player who got something to prove, assuming he hasnt breaken his leg over past couple of seasons (Ronaldo being an exception), and mentally weak. The motivation to do well is not reflected in his past two seasons record. I am confident that Samuel will do well here.
Secondly, Camo isnt getting any younger. Camo is at the peak of his game, and his value as a player will only dwindle with time goes by. Mancini is only 26, and has a best of years ahead of him. I think we are realistically looking to challenge in 2 to 3 years, and Camo will be past the sell out date by then. Mancini will be entering his peak years.
And lastly, I think Mancini provides more penetration down the flanks. It seems DD is intent on playing two defensive midfield next season. Paro is technically proficient, but so was Viera. And neither of them are creative force Zizou, Ballack, Pirlo are. I think it is vitally for the team to have genuine penetration down the flanks. Camo is superb tactical player who gives you all round game, work rate (highly under appreciated facet of his game), and cover to defence. But going forward Mancini is superior IMO, and his goal could be real value to the team which lacks creativity in the midfield.