If it's 1:1, you're switching XP spend to boost Endurance instead of on that stat or ability. To my mind, the whole point of canister use is to replace XP spend.
For skills like spells or shaping, yes, I can see the END cost being a good idea, but (speaking personally) I would always use a stat or ability-boost canister (especially for weak sections), but not necessarily a spell or shaping canister (some are immediate candidates for the Purifying Blade). I often don't even both training or learning shaping or spells outside my 'speciality'.