Speevy,
If you get unreliable airspeed in the cruise suddenly with smooth flying conditions and everything normal then 5 degrees climb power may not kill you straight away. However, in a realistic scenario, with moderate turbulence, by the time you realise the aircraft has unreliable airspeed it's going to be possibly over 20 seconds from when it occurred. As a result your airspeed may already be far too high/low. By then pitching UP to 5 degrees (it will be a pitch up as you don't have 5 degrees pitch in the cruise normally) you are potentially worsening the situation. A slight overspeed is better than a low speed. Yet again, there is no procedure from Airbus for this situation. Your point of 5 degrees CLB was not designed for this scenario, let alone the fact that if your at your ceiling this is potentially disastrous.