All engines are 'deliberately de-tuned' by the manufacturers to prolong engine life, some, like VWG, sell them for a few years then offer a 'tuned' version for many £'s more - which is nothing more than a software update, so I wouldn't worry too much about that!
The problem with that particular engine is that it was rushed into production, in a configuration it wasn't tested for then had emissions regs imposed on it that it was never going to pass without compromises to it's longevity - particularly on commute / school run low power, low temperature, high DPF load journeys - i.e. 80-90% of the target market. Honestly, unless you're doing significant long journeys, petrol engines are by far the best option, the little extra you spend on fuel is nothing to the extra you'll be spending on maintenance & repairs (and yes, the hypocrisy of typing the above and owning an SDV8 that does 6k miles a year isn't lost on me).