Whichi is better for publishing book on DocBook 4.5 or 5

Hello,

Currently I've start translating technical book into japanese using 
DocBook. But unfortunately, I'm not sure which version of DocBook which
is 4.5 or 5 suitable for doing that because of lack of my experience.

I'm now concentrating on translation from English from Japanese.

Please tell me latest pros and cons about each version.

Best regards,
Akihiro Moriguchi