granted the guys have covered everything here,
but I have to kind of agree with sureno on the 61 - 88 key versions,
fair enough a child has small hands, but they are going to grow and a 49 key could mean more understanding of the sequencer is needed?
how advanced is the lad?
I'm no expert at classical or Jazz, but I can only imagine that its not going to be possible to play every piece over 49 keys at one time!
is there a Piano in the house or is this also going to be used for practice?
how much understanding of the sequencing software do you have?
I would atleast look at further saving and get a 61 key because at some point in the future you are going to want to upgrade!!