I asked this question in the Wisdom of the Crowd:

Should Dr. Tan Cheng Bock set up a new party?

Here are the responses: (74 Votes)
64 % - It is better for Dr. Tan to lead a coalition of the existing non-PAP parties.
16 % - It is better for Dr. Tan to set up a new party and attract its own members.
11 % - A coalition of the smaller non-PAP parties will not be credible anyway.
9 % - The new party will split the non-PAP votes.

See the pie chart at: 
http://www.wisdomofthecrowd.sg/chart.aspx?ID=1030