Only disadvantage of using the concurrent licenses, suppose you have many developers who named as concurrent user, if you don't have enough concurrent licenses, then some of the concurrent users will not able to login, because all the licenses are consumed.
For example, you have 25 concurrent licenses. you have 50 developers and 50 users (Just viewing the reports). If you name all the 100 users as concurrent users, 10 developers and 15 users logged in to the system at the same time, then your 25 licenses are consumed. Now if any developer wants to try to login , try to do some development, then he cannot login, since there is no enough licenses left.
So best practice is name the developers as named users and regualr users just want to view the reports, name them as concurrent users. of course you need to have licenses to support them.
