Considerations for Wiring for EI ECU

[walkman]

I'm planning my EI installation and thinking about wiring.

I'm considering wiring the ECU directly to the battery rather than off the main buss (controlled by the master switch and contacter) via a 7.5a pullable breaker in the breaker panel and thence to a locking toggle switch by my mag/starter switch.

I would like to have an LED annunciator (green) next to the toggle switch to indicate when the ECU is powered up. Mostly for the ability to glance back into the cockpit after parking to make sure I turned it off as I'm likely to leave it on otherwise I'm sure I could make a safety argument for an annunciator as well.

Is there any value (safety or otherwise) in wiring directly to the battery? I've never turned my master off in flight, but I suppose there is always a first time.

Any suggestions for wiring the annunicator? Simple as a green LED one side on the switched side of the switch and the other to ground?

EDIT: In further retrospect one concern about wiring directly from the battery rather than via the main buss is that the wire from the batt + to the panel breaker will not be protected. There is a trade off between using the main buss, which is fed via the master switch controlled contacter and a large (2?) gauge cable but suffers from the potential of inadvertent in-flight master switch operation or failure of the master switch and/or battery contacter, or wiring directly to the battery and having the 18 AWG wire between the battery and breaker a potential issue of shorting/overheating/fire.