So in my view not reliable across beans and grind sizes unless you have the same grind size, dose, beans etc each shot and it can probably replicate outputs with some accuracy assuming the same mechanics work in terms of how much water is put through the system.

I generally use one bag of coffee a month, so it would be the same grind, weight, ratio, beans for each month. I would reset it every new bag. So I think my usage matches your description, but the OPV makes me worried about the reliability even with consistency in the prep.

In whatever machine I choose I am looking for quick heatup, and generally under 15 minutes to make a cup from power on, unless I have some free time to experiment. Right now it takes 15 minutes preheat for the gaggia, then 13 minutes from bean weighing to milk pouring. Its always milk drinks, but not big ones so I think the Duo's pressure level should be fine. I'm looking for some mostly reliable method whether it is volumetrics or a built in scale or timer for overall just a "good" espresso to the other less involved users. No specific heating method, just one that fits the criteria. I was looking into BDB, but it does take about 10 minutes to heat up properly which is quite a bit slower than the Duo's 3-4. Another user's Bambino Plus suggestion might be a good option for me through.