Huge data centric web applications

I have a choice of choosing one of these two things:

1. Use a spreadsheet based file (xls, csv etc) to upload a bunch of 开发者_StackOverflowdata(mostly two column tables) which is processed by the application and gives out the result as a spreadsheet file to download.

2. Completely use web based interfaces to store, edit and save the data without the use of spreadsheets at all.

Could someone please enlighten me on what are the pros and cons of both ?

Usually non-tech people like to use their own files when doing this type of operation because it's something they have control over. They can send them to other people, keep their own tracking, do stuff on the output data in Excel (formulas, graphs, analyse the data on their own without asking you to enhance the application, etc)

Also when dealing with large amount of data it is impractical to manually work on such a large number of "rows" (type values, change, etc). The page might crash so you have to input everything again, etc

My view is to go for files, they seem more flexible and better suited to business (non-tech) people.