Quick advise regarding Cyrus migration

[Roman Medina-Heigl Hernandez]

Hi guys,

I'm running Cyrus Imap 2.4.16 on Debian 7 (x86) 32 bits and I need to
migrate to 2.4.17(nocaldav) on Debian 8 (x86) ** 64 bits **.

I've been reading some articles (like this one, which is 6 years old: 
https://cynici.wordpress.com/2010/12/06/how-to-migrate-32-bit-cyrus-imapd-mailboxes-to-64-bit/
).

My question is: is it really needed to convert .db from skiplist to
flag, and then back to skiplist , as suggested by many articles? (or
even rebuild mailboxes like in last pointed article). Both machines are
x86, being the only difference 32 vs 64 bits (endianness is same, etc).

I did a quick test simulating the migration, by simply just copying
/var/lib/imap, /var/spool/mail and /var/spool/sieve. It seems it worked
fine (or at least I couldn't find any problem when running imap with the
migrated data). But I'd need your confirmation this should be sufficient
and I won't find problems in the future.

I also played with db conversions (skiplist -> flat -> skiplist) and I
have some questions:
- I converted annotations.db (skiplist) to flat and then back to
skiplist. It passed from 11K to 144 bytes (both skiplist)!!! Is it normal?
- I did same exercise obtaining new skiplist db in both machines from a
same flat. I got a vey similar (but not exactly the same) result .db in
both 32 & 64 bits (some minor bytes may change but it didn't seem like
big differences/changes). Maybe some different metadata (I mean not
important), or I should concern about it?
- apart from .db's from /var/lib/imap, should I worry about other
skiplist like .seen files in /var/spool/mail?

Sorry if there are too much questions but this migration is important, I
cannot loose any data (email data + email metadata: read marks, etc).

Please, advise!

Thank you so much in advance and have a nice day!

-- 
Saludos,
-Román