Ophelia ... nice to meet you.
Why all the concern about 15 minutes less at the public talk? Can't imagine how you expect to cope when things get tough if this throws you off so much.
Why would you ask this question here? Most posters here are not Witnesses so how can you expect them to give a proper answer?
Ask your brother and father what they think and let us know what they say. 15 minutes less each week sure doesn't sound like a deal breaker to me.