I wouldn't worry too much about power loss during a firmware update, each of those components can recover in reality should they suffer a power loss during updating. It's best not to interrupt such process but using a 1500 KVA should be enough to keep it running until it finishes. The chance of an update happing during a power loss is slim as you would have to hit it at the right time. Upgrading during such a time would be rare I would think. Now for having a projector in a power loss prone area makes sense to me. Projects need to cool the lamps in order not to diminish life etc.
Jut my 2 cents
My Main HT-Setup
LG OLEDE7P - Denon AVR-X4200W - Definitive Technology Mythos STS - ProCenter 2000 - SR-8040BP - A60 for ATMOS - SVS Ultra-13 SUB- Xbox One S - DirecTV 4K - Sony Blu-ray - Panamax Power Center - Microwave oven for Popcorn