After buying beans at the supermarket for a while, I went for the first time to a local reputable roaster today to buy beans for espresso and asked for a recommendation. The answers seemed surprising:

1. Customers don't like getting the dark roast by itself since the beans are too oily and can clog the machines. Instead, they recommend mixing medium- and dark- roast beans 50/50.

2. They have grinders and an espresso machine, but they only prepare samples using their own espresso blend but none of the other beans.

3. When I asked for the roast date, they said about 1-1.5 months ago. Their website says they roast daily.

My questions to you:

a. Does any of that seem reasonable?

b. In particular, do you ever mix medium- and dark-roast beans, then grind and pull them together?

Mixing roast levels is called mélange blending, or mélange roasting. As an example, I have found that it works very well when blending certain beans/origins for a medium-roast-level omniroast.

Mocha-Java, which some say is the oldest blend, was/is a mélange blend of medium-roast Yemens (shipped from the port of what is now spelled Mokha) and dark-roasted coffee from the island of Java in Indonesia (although now the name Mocha-Java is used for almost anything).

The four-six weeks thing again depends on the coffee and the roast.

Nothing unreasonable, but you're unlikely to find those techniques used in light-roasted third-wave specialty coffee.

I have tried mixing med roast beans (25%) with dark roast beans (75%) and quite liked the result -- it is obviously dependent on the beans, the ratio, and what you like.
IMHO I can't imagine buying beans that old -- typically the local roaster I order from ships beans the day that they're roasted or the day after, then they take a day or two to arrive. The bag should have the roast date on it. Lots of posts with opinions on the optimal post roast "age".

Mixing roast levels is called mélange blending, or mélange roasting. As an example, I have found that it works very well when blending certain beans/origins for a medium-roast-level omniroast.

Mocha-Java, which some say is the oldest blend, was/is a mélange blend of medium-roast Yemens (shipped from the port of what is now spelled Mokha) and dark-roasted coffee from the island of Java in Indonesia (although now the name Mocha-Java is used for almost anything).

The four-six weeks thing again depends on the coffee and the roast.

Nothing unreasonable, but you're unlikely to find those techniques used in light-roasted third-wave specialty coffee.

Very interesting, thank you.

I have tried mixing med roast beans (25%) with dark roast beans (75%) and quite liked the result -- it is obviously dependent on the beans, the ratio, and what you like.
IMHO I can't imagine buying beans that old -- typically the local roaster I order from ships beans the day that they're roasted or the day after, then they take a day or two to arrive. The bag should have the roast date on it.

The beans were 50% Guatemalan medium roast and 50% Sumatra dark roast, per the staff's recommendation.

My first attempt was 17g in, 38g out, in approximately 28 seconds. It tasted balanced and milder than the 100% dark roast I am used to, good overall. There was a lot more crema than I have seen with the other beans, for what it's worth.

I was very surprised when they said that the beans had been roasted that long ago. I expected it to be in the last few days. The bag doesn't indicate the roast date as they made a custom blend from bulk bins and put it in a new bag.

In the late 90's, when darker roasts were common, but I was tiring of them, I roasted the same bean at two levels and blended them that way. I wanted some well developed flavor, and even some roast smoke, but didn't want to sacrifice the nuance happening at lighter levels. Back then I thought it worked well for a Sumatra but is not something I've ever returned to.

I blend on the fly almost every morning for a 40oz pot of drip brew. I often prefer the more complex yet balanced flavor profiles I tend to get from blending. I almost always have some darker roasted Indonesian beans to add that body and texture as well as moderate sweetness and roastiness. With that I'll usually have something lighter, brighter and fruitier to add to the blend and perhaps a medium to medium dark roasted South American Brazil, Peru or Colombian to round it out. I weight these out as percentages, say 50/25/25 and throw it all into the hopper and then grind away.