Not too difficult
We recently changed ours. We have a 1988 Catalina 30 which had the typical "rats nest" behind the panel. Simply swapped out the old one, put new ring connectors on the existing wiring (after making sure they were not corroded), cleaned up the layout with appropriate ground busses, etc. We did use the Seaward panel which is very nice and of high quality (if expensive). Highly recommended since it fits perfectly and is pre-wired for the most part.Gary Kunkel