Didn't realise the Spaniards were so hot on nicking bikes. Had it happen to me once before in London, more due to my own stupidity and it's a lesson I learned very quickly! Still doesn't take away from the fact it's a shit thing to do!
We're you going downhill when you had your crash, Málaga? I never ever got round to trying it on a mountain bike, feel I don't have the balls to do it these days. Get the fear, despite being OK gunning it down a road on a road bike! Can imagine there would be some cracking down hills there.
One of my bosses regularly spends 3-4k on a bike, I say regularly but he's done it three times since I've been there (over 7 years). It's easily done, but I don't think it's worth it unless you're doing comps or something thats time dependent. Have a very good spec on my bike, for what I need it to do, but upgrading would only see marginal gains. Doesn't seem worth it. That said, might be different for a mountain bike! You got disk brakes on yours?