Evan, thank you for the time in sharing your thoughts on how handoffs should be handled. I completely agree with your statements, and I want to input my personal experience with working a neighboring ARTCC during the event.
I worked ~5 out of the 7 hours on Cleveland Center, and witnessed approximately 4 controller changes. I had signed on a minute after the event had started and I was misinformed of the center splits occuring during the event since there were several, and I mean several.
Communication is key ... if controllers in-facility, and out-of-facility do not coordinate with eachother in the proper means of communication there will be misinformation, and possible confusion that occurs. The event had a great amount of traffic, and I handled several handoffs. The first thing I did: communication, and I asked what "sector" I would be handing off to. But this is my first mistake ... controllers should be inquiring what frequency they should be handing off to in certain scenarios if... for in this case the sectors are unknown through the callsigns. I was then politely informed that the high sector for our boundary was on frequency: 127.970, and also informed that the sector split was not yet active.
One the frequency has become active there was a great amount of coordination occuring, and the event went as planned until... the controller change. I was unaware of the changes occuring frequently over the span of the event, and I was unaware until my first handoff was rejected. This is my second mistake: not looking frequently for the frequency I was handing off to, and no knowledge on the new high sector ID handling my boundary handoffs.
New Lesson: in scenarios where you may fortunately border a facility with an event, and controller changes, or no event: you should always keep an eye out on changing sectors and frequencies. I always keep my communications "tab" open on my, lucky to have, second monitor, and I utilize this to my advantage. I would also like to give the advise for other controllers to make my mistake, and use this lesson to remember that "scanning" non-scope material and systems is important to the efficiency of our traffic management flowing between our TRACON and ARTCC/FIR boundaries.
I am not ashamed to say (as no one should be); I learned from my mistakes, and take this from me..... be informed/in the know of the sectorization of your neighbors (especially for events), and scan not just your scope, but your other materials and systems (such as SIGMETs/IDS/Comms.)...
A great learning point for myself, and I hope you inherent the other materials regarding the responsibility of handing off... and please be nice to your neighbors.