Pudge, I've never even seen the shoes you describe so take this with a pinch of salt, but I do have a lot of experience of marching in hobnail boots. On tarmac/rock they're lethal - like being on iceskates - particularly if it's wet or icy. So I'd view these with a certain amount of caution. You may find you go arse over tit on those slabs.
As a fellow back of the packer (and shopoholic) the thing I've spent money on this year which has made the most difference to my running is coaching. Doesn't stop me lusting over the new garmins, mind, but I'm resisting as shiny thing don't make me run better. Money on coaching does.