Funny thing is...Passport Canada don't require the updated name on the citizenship certificate anymore...just the certificate of name change, so this was a complete waste of time and money (for me at least).
That said, I'm still reluctant to change the name on my passport because what if IRCC actually lost my package (along with my citizenship certificate)?! In that case, I'd have to submit a replacement request, which presumably will require an ID with my full (old) name on it because that's the one they have on file. I've already changed my name on all my IDs except my passport, so I'm stuck with the old name for the time being.
I really can't wait for the day I never have to deal with IRCC ever again...15 months to change a name on a certificate? What a colossal joke.