Modifications to standard business views and application grids

I have a new interface with an expense management tool and there are certain values I am passing to user reserved fields URRF and VR01 on the AP Ledger F0411. I also want to add these fields to the business view V0411E Voucher Document Review and Grid on Form P0411 W0411G Supplier Ledger Inquiry. My question is, what are the possible ramifications aside from maybe performance? I know modifications to standard objects can be considered bad practice, but in this case do I need to be concerned about data issues also?