Intrinsic rewards have a long-term advantage over extrinsic rewards because the employee really is into what they are doing and are not motivated only be their pay. This is a great way for a manager to ensure that they have the correct staff members working for them because in the long run the employee will give their all in terms of research and development and will not feel like they have to be rewarded always for what effort they put in. As an aspiring manager it is important to be careful during the interviewing process to ensure that careful attention is taken when it comes to the employees reaction towards work, that is what motivates them to want to work hard, external rewards or internal rewards. This is a good gauge I would think to use to steer one to choosing the correct individual for a particular job.
There is a fine line as to how an employee works and how fairly they think they should be treated. If an employee works hard at work and is rewarded fairly, they are further motivated to work harder and to contribute more towards the company. On the other hand if an employee works really harder than most and is compensated the same as others, this may pose a problem. The employee may not feel like the work they have put out is justified because they have received the same pay cross the board. So I do think that equity at work is important although it may present problems if employees know their reward system and how everyone is compensated.