There are SIGNIFICANT advantages to doing an integration instead of a compete replacement.
Integration to legacy field devices can save up to 90% of the cost of doing a complete replacement. This becomes more evident as the size and complexity of the building increases.
If you do a phased replacement the customer can include the incremental transition costs in their maintenance budget. They do not have to do a onetime large capital outlay.
By integrating and replacing the head end they gain most of the same benefits of a complete replacement day one.
Make sure that you are looking at the complete cost of a replacement system. It’s not just the hardware. All of the installation and commissioning services need to be considered.