You have two later flights to choose from if you do try for a change. Both flights land after midnight. Looking at it another way there are two later flights that AC can try to fit you on if you miss the connection. What is LH's OTP (On time percentage) like on the MUC-YYZ flight?

I guess it is all about your risk tolerance. What are the consequences of missing the connection? Do you have an important event the next day? If there is no room on the two following flights, are there big consequences for not arriving until the next day? If there are no business class seats left, do you care that much about the seat on a two hour flight if you miss the connection? AC has about 10 YYZ-YHZ flights per day. If you need to stay overnight in YYZ, will AC put you up on a business class award ticket? If it were me, I'd be happy to be put up in a hotel in YYZ and take a next day flight instead of landing in YHZ after midnight local time while my body clock was still on German time.