Considering the number of moving parts in the IRS, I would rather they stay on the old and proven until/unless a robust new system has been designed from the ground up, and has been tested over at least 5 years by running in parallel to the current system. If you want to get a sense of what goes into the IRS systems, search for the ADP codes manual for the IRS. It's hundreds and hundreds of pages of codes for just about everything under the Sun.