Perhaps light grey overhead and Japan black lower. How high are your ceilings? Inspiration shots below. I agree 2700 would be too high in black but 2400 would be fine.

One step at a time. Do painting as planned then sit back and look. You might decide the fresh timber is a great complement to the grey.

I was in favour of a colour similar to Jarrah but my daughter disagreed. My concern with black is that the decking is a shade of blue/grey and the house has much grey as well. I really like the black(ish) look but the pics shared show it on quite light surfaces i.e. cement or a very light wood colour. I actually have a full tin of blackbean wood stain. Do you know this colour?

Hello .. why not grey but not too dark. A neighbour paint their fence (beside a 70's but lovely yellow brick home) a dark grey. I wondered if it might be a little too dark even tho that appears to be the trend. I have too, a 70's yellow brick home and deciding what shade of grey I might paint the paling fence in a courtyard area. I think maroon (trim) and grey would work nicely and it's surprising what a new appearance does for the surroundings. I'm often amazed.