Mass data loads to the production client

Since you are a functional consultant I am going to recommend the use of CATT (transaction SCAT). They are fairly easy to learn and use for uploading data. Honestly though, for only ~200 updates I would probably do it by hand. A team of 5 could have it done in no time but you do introduce the human error in the equation that way. For large loads of data (large really depends on where you are at, my current client would probably consider that be at least 50,000 updates) I would recommend doing development with ABAP. By using ABAP you gain many valuable methods of reporting and fixing an errors that occur. Also there is the element of reusability.