I will go contrary to most of the posts here and say get the DA (L) 35/2.4 for the moment then get the 31 when you can. Every decision comes down to money and if you've already got it set in your mind that the cost of the 31 is attainable, then why not? There can be only one.
If you love the feel of using the 43, the plasticy FA isn't as good. There is something to be said for aesthetics and feel in the hand, isn't that worth something?
For the people who recommend the FA 35 instead, why didn't you just get the optically identical and much cheaper DA 35/2.4? Hmm?