OK, first I'm not at all familiar with the CEC, as I'm stateside.
As to your inquiry, No, I have not seen any situations of damage or problems with undersized neutral conductors in systems as you described.
Occasionally I come accross a spec with a 'undersized neutral' by a PE/EE. Upon review of the plans and the loads, I may elect to install a full neutral and send a CO to that effect. Please note that the 'load' must be considered; if it's into a panel, I prefer a full neutral, primarialy based on future modifications. Note that this is my opinion, and NOT based on NEC requirements. We perform a lot of repeat work at the same complexes, and always try to 'think ahead', within reason.
Also, if you are bidding, you may end up 'high' if you do not follow plans and specs without offering explanations (if possible)
John
