I'll give you a quote from an essay by John Terraine on the Battle of Amiens:

It was a well-established fact that when either the Australians or the Canadians appeared in a sector trouble was brewing. This was particularly true of the Canadians because of their Government’s rigid insistence that their divisions should never be separated. It was, therefore, necessary not only to hide completely the presence of this Corps, 100,000 strong, which would have to be in the front-line at zero hour, but also to hide the fact that it was no longer in the sector, far to the North, where the Germans would already have identified it.

A number of improbable reasons for the success of the Canadian Corps have been bandied about, but none of them stand up to scrutiny expect for the fact that the Canadian Corps was the largest single cohesive fighting unit in the entire BEF - what's more it was experienced as a unit. Most other Corps were fairly amorphous. Brigades and battalions would come and go, but the Canadian Corps was maintained intact from Vimy through to the end. This engendered a better degree of trust and cooperation between staff and fighting officers, and between the officers of the different subordinate formations, and thus ensued improved efficiency and efficacy overall.

What's more the Canadian Corps was unusually large (at around 100,000 men, it could field more fighting troops than today's British and Canadian armies combined). This was because the Canadians were able to resist the cutting down of Brigades from 4 to 3 Battalions, and maintaining 4 active Divisions in the Corps instead of 3.

So yes, its no exaggeration to say they were viewed and used as 'Shock Troops' in WWI due to the Canadian Corps' superior organisation and structure.

Edit: Just for the sake of balance - it was not only Canadian or ANZAC outfits that were capable of great feats of arms. Arguably the most astonishing success of the entire war was the breaching of the Hindenburg line by the St Quentin canal by the 46th (Territorial) Division - a thoroughly ordinary British infantry Division that had up to that time completely failed to distinguish itself in combat. This emphasizes and important point: That the success of the BEF in 1918 was not down to a few elite units, but to the overall proficiency and fighting skill of the army in its entirety.