I dislike the idea of three councillors. While you point out that it cuts down on unnecessary positions and makes things run more easily, I worry about the ease of abuse and the jobs that might be affected.
With 5 councillors there is an odd number (which is necessary to prevent ties in voting). As well, if one councillor is away or temporarily unable to preform his/her job, then one of the other councillors could pick up the slack. With only three councillors each of them will likely be tied up doing their own jobs. As well, three is a small number, and the saying goes "security in larger numbers" meaning that it is more difficult for corruption to happen in a very large group as opposed to a small group. (of course, the line has to be drawn somewhere, security in numbers does not mean that we need a council of 50 people).
I saw no issues with a 5 person council. Although I'm going to agree with Chacal "this proposition is better than the previous one, if you believe we need a leadership."