I think it all depends on the child. Sounds like you've made your decision as to what feels right for L. For us I do think Emily (Feb 2009 baby) will be ready for kinder in 2013 and prep year after. I do worry at times about her then being the youngest cause so many kids now are staying home that extra year.
I'm planning to just keep eye the next 2 years and see how she goes. The kinder were hoping to get into is very good and kids have done an extra year if they have needed, they're not automatically just pushed into school. So we'll just see how she goes.
Its just annoying 3 year old kindy they have to be 3 by end Jan but 4yr old end april, should be more consistent.