After 3 passes with CCE you will see negligible improvements. There may be a little, but not worth the time.
I don't agree with TimC's assessment of DVD2SVCD's quality, but it is best to try these things for yourself and see if they meet your requirements.
I use ProCoder2 for this process, 2 pass vbr usually.
Edit: I don't think I was clear---3 passes with CE will improve your output considerably, but running more than 3 you will get diminishing returns.