prateekmedia I maintain the core database on my primary computer. The database file is stored in my documents folder, separate from the app itself.
Every time make a password/site add/change, I copy the database to a USB stick that I keep for that purpose, so the stick is always current between monthly data backups. I copy the database file to the documents folder of the other three computers monthly, when I change my entire password set every few months, and when I change/add a critical (that is, frequently used) password/site. It takes just a few minutes to copy the database file to the other computers.
The reason that "manual sync" works for me is that my password set is relatively stable, I use only about 10-15 passwords on a regular basis and store less than 50 in total. It would not work if I frequently added new sites and/or changed a significant number of passwords daily/weekly.
I try to avoid storing anything online, so it is worth the bother to copy the file. I do keep two e-mail passwords in Firefox sync so that I have access to e-mail on my iPhone, but I don't otherwise store passwords online.