upgrading with murder/aggregator

We are looking to migrate from a 2.3.7 server to a 2.4.18 server.  I was
hoping to set up the cyrus murder/aggregator and move the existing
server behind that.  While doing some reading and research, I came
across the following mailing list thread.  I was wondering if it's still
the case that the frontend needs to be the same version as the older
backend?

https://lists.andrew.cmu.edu/pipermail/info-cyrus/2010-May/033061.html

Aside from the compatibility between frontend and backend, there was
also a comment about having to recompile the sieve filters per the other
post below.  Is that still the case moving from 2.3.7 to 2.4.18?  Are
there any other gotchas to look out for?

https://lists.andrew.cmu.edu/pipermail/info-cyrus/2010-May/033056.html

Thanks in advance,

Pat
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