Kevin Martin is an awful defender, significantly worse than Ray Allen. On top of that, he is injury prone.
Is he a better player than Allen? Yes. Is he a better fit? Probably not, given how well Allen has accepted his role on offense and defense.
And the bottom line is that with or without him, we'd still need KG to really have a shot at the title.
In any case, there is absolutely no way the Kings are doing this trade. All Allen would offer them is cap relief, but they will already be under the cap next season. And while Nocioni's deal is bad, you don't trade a player like Martin to get rid of a 7 mill contract.
Bottom line is, this trade will not happen, and even if it did, it would not improve our chances this year all that much.