Thanks for the reply; the last feature is pretty cool. I'll certainly have a play with the free 'dabbler' edition (I forgot what it was called), but it doesn't sound like there's much to tempt me away from Mathematica for the time being. I use the CAS stuff a fair bit now.
Mathematica 10 is being released shortly, that has plenty of new things (thanks to the Wolfram Language it shares with the Programming Cloud) to tempt you! GeoGraphics, Entity, computational geometry, machine learning, Association, Dataset, SemanticImport...
