If I was Mace I would have at least bring Anakin with me. I mean, Mace should know that sidious should be stronger then dooku, who was quite stronger then any of the jedi he brought and even a match for him, and that he also could mask his presence in the very presence of the jedi council, so he should know he was fighting a sith lord of immense power... I know Mace didn't trust Anakin, however the true is that it was Anakin who told him who sidious was, so If I was mace I would bring anakin with me and say to him that if sidious was finally arrested/killed he would finally become a master as he so desired. Bringing shaak ti and cin dralling was also a very good option, as also warming the entire jedi academy of what was happening.
I believe that if mace had at least brough anakin, he would see sidious killind the other jedis and so by helping mace he wouldn't probably cut off his arm as he did. Anyway, the true is that what caused the jedi's downfall was obi-wan. If obi-wan was on coruscant, his influence wouldn't allow anakin to turn in the dark side, and so sidious would be screwed.