I've searched a bit on this topic and found a few results. However, I'm looking for if anyone knows about or could point me to to some authentic or reputable case studies that detail the benefits(particularly performance) of migrating from MyISAM to InnoDB.
Nice if you could point to any that is about MySQL version 5.5 and above which has InnoDb as default storage engine.
As you are no doubt aware from your searches, InnoDB is primarily better than MyISAM for high volume inserts (not counting non-comparable features like Foreign Keys or Full Text searches, which are exclusive to InnoDB and MyISAM, respectively), while MyISAM is primarily useful for tables which are read more often than they are written to.
That said, an article from the MySQL Performance Blog is perhaps relevant to your particular interests:
High Rate insertion with MySQL and Innodb
To a lesser extent, this SO question as well: MyISAM vs InnoDB.
EDIT:
There is also a webinar about migrating from MyISAM to InnoDB, although I have not watched it. The description seems to deal with MySQL 5.5 having made InnoDB the default, though, so again, perhaps it will be useful. You can access the webinar directly at http://blip.tv/file/4905943.
This issue is actually well addressed in the DBA StackExchange
https://dba.stackexchange.com/questions/1/what-are-the-main-differences-between-innodb-and-myisam
https://dba.stackexchange.com/questions/194/how-do-you-tune-mysql-for-a-heavy-innodb-workload
https://dba.stackexchange.com/questions/2885/should-i-move-to-innodb-during-a-planned-migration
https://dba.stackexchange.com/questions/5119/convert-table-from-myisam-to-innodb-without-downtime
In my years as a MySQL DBA, I have personally converted dozens of MySQL Databases for my employer's WordPress and Drupal Clients. The immediate benefit was the elimination of table locking issues in high-read, high-write environments.
来源：https://stackoverflow.com/questions/7335515/migrating-from-myisam-to-innodb