Is it OK for users to use either of a pair of replicated servers ?

[John]

Further to my last message, I've updated my master so now both servers 
report the same version:

version    : v2.4.17 d1df8aff 2012-12-01

I'd like to understand some error messages that I am getting and what I 
should do to resolve them...

On the replica:

syncserver[8816]: higher last_uid on replica user.myuser - 57628 < 57629
syncserver[8816]: higher modseq on replica user.myuser - 36186 < 36187

On the master:

sync_client[5197]: MAILBOX received NO response: IMAP_MAILBOX_CRC 
Checksum Failure
sync_client[5197]: CRC failure on sync for user.myuser, trying full update
sync_client[5197]: SYNCNOTICE: record mismatch with replica: user.myuser 
more recent on master
sync_client[5197]: SYNCNOTICE: master uid:57626 modseq:36180 
last_updated:1359731641 internaldate:1359729048 flags:( NonJunk)
sync_client[5197]: SYNCNOTICE: replica uid:57626 modseq:36177 
last_updated:1359730649 internaldate:1359729048 flags:(NonJunk)
sync_client[5197]: SYNCNOTICE: record mismatch with replica: user.myuser 
more recent on master
sync_client[5197]: SYNCNOTICE: master uid:57626 modseq:36180 
last_updated:1359731641 internaldate:1359729048 flags:( NonJunk)
sync_client[5197]: SYNCNOTICE: replica uid:57626 modseq:36177 
last_updated:1359730649 internaldate:1359729048 flags:(NonJunk)
sync_client[5197]: SYNCNOTICE: only on replica user.myuser 57629

Despite these messages, my replication appears to be working but I can't 
as yet be 100% sure. I'd like to understand the above and try and stop 
them if I can...

I can't find any documentation detailing what the above means, and I'm 
not that familiar with the internals of the imap server, so I'd really 
appreciate some pointers...

Thanks very much.