To use DLLs or Add-Ins ?

Hi,

I have some VBA code which extensively reference the cells in the workbook where it resides. I need to distribute the code so that the users can call my macros from their spreadsheets. I've done this by creating an Add-In out of that workbook.
Would creating a DLL out of this code be of any advantage? (My functions will only be called from an Excel spreadsheet) Also, can the functions inside a DLL, reference any workbook cells?

Thanks