Germany was also in a somewhat better position prior to the crash than we were so weathered it better as it could afford the spending needed. However that investment seems have delayed problems rather than solved them as their economy is struggling (relatively).
Germany has sunk the whole eurozone with its pointless brutal approach to Greece and the other PIGS. Austerity is just as bad a policy over the channel as it is here.
I am not sure things would have been as rosey as you think. Worst case we could have had just as much stagnation but with an even higher deficit and higher borrowing rates.
To be clear, I don't think Labour's plans would be 'rosy' - they were far too much austerity-light for that - but we would be in a better place now than we are. Darling was a vastly more competent chancellor than Osborne is. The really sad thing is that the coalition has been sitting there with the best chancellor of the last forty years or more right there in cabinet twiddling his thumbs while Osborne trashes our economy.