Is it neccessary to recreate rollback seg to the average size.

Fellow Dba's

In one of our production database which I support, There are 30 rollback segments with Initial 15m ,next 15m ,optimal 30m ,minextents 2 and maxextents 249.When I run the tuning scripts, I saw the average size of the rollback segments are around 5megs. Except 2 rollback segments which have the average size around 12mb and the HWM is 61mb.(due to some long running batch jobs)
There is no shrinks or extends(except the 2 RB's). So I have planned to recreate all the rollback segments to the new storage (initial 540k,next 540K ,optimal 5400k minextents 10) in the next maintenance window to reflect the average size of the rollback.

My questions are
1. Is it really neccessary to recreate all the rollbacksegemnts to the average size to get a better I/O performance.(offline,drop,create & online)
2. Is it possible to recreate the rollbacksegements when users are online. (since it is very difficult to get a maint. window) 3. I already have 30 rollback segments . I got the advice from my senior dba that to increase further 10 Rollback segments. (total to 40) Is it really a needful thing?

Thanks in advance...
Note: Oracle 7.3.3/Aix4.2/65gb total size/Tuxedo app Received on Tue Oct 19 1999 - 12:36:37 CDT