I used my standard brewing ratio of 40 ounces (1.2 L) of water to 2.3 ounces (66 grams) of medium ground coffee. I also tested with my default whole-bean coffee sourced from Costco (Kirkland Colombian Supremo).
Another key factor to brewing quality coffee is sticking to the ideal water temperature (197 degrees Fahrenheit, 92 degrees Celsius to 205 degrees F, 96 degrees C). According to Bonavita, the Metropolitan uses the same 1,500-watt heating element and "advanced heating control" as the Connoisseur. My test results didn't agree. Thermocouple readings I took inside the brew basket indicate that this brewer is more aggressive but less precise.
Within the first minute the average temperature inside the grounds had already leaped to 190.5 degrees F (88.1 degrees C). At this stage the Connoisseur had only hit 147.9 degrees F (64.4 degrees C). By the second minute, temperatures dropped slightly to 190.1 degrees F (87.8 degrees C). During the third minute, the needle reached 194.3 degrees F (90.2 degrees C) and began to steadily climb.
Here by contrast the Connoisseur's brewing temperature stayed firm. Temperatures hovered no more than 4 degrees F above 194.6 degrees F (90.3 degrees C) through the rest of its brewing cycle. Not so with the Metropolitan. Its grounds reached a steamy average temp of 199.3 degrees F (92.9 degrees C). That comes to a wide fluctuation of 9.2 degrees F.
My refractometer tests mirrored these swings. The Metropolitan notched closely grouped but varied TDS (total dissolved solids) percentage results across four runs (1.3, 1.2, 1.1 and 1.2 percent). The Connoisseur was more consistent (1.3, 1.3 and 1.4 percent) during its three test brews.
These numbers from the Metropolitan convert to an average extraction percentage of 19 percent. That's still in the ideal range, commonly considered to be between 18 and 22 percent. The Connoisseur had a slightly higher average of 20 percent, dead center of the sought-after spread.
Quibbling over numbers only goes so far. I'm happy to say that the drip this brewer made was every bit as good as what I tasted from the Connoisseur. Drinks made from my humble test beans had all the delicious flavors I expect. Specifically I detected rich chocolate, cinnamon spices and no unpleasant bitterness.
One aspect of the Metropolitan that's sure to be a deal breaker for some potential buyers is its glass carafe. Its supporting warming plate shuts off after 45 minutes. After that, brewed coffee inside starts to cool quickly. It took just 1 hour before temperatures inside the pitcher fell from a high of 174.3 degrees F (79.1 C) to below 150 degrees F (65.6 C). That's brief compared with the 3 hours and 31 minutes before heat escaped the Connoisseur's thermal carafe. The Moccamaster's insulated carafe remains the one to beat (6 hours).
Not for slow drinkers
Whether to buy the $100 Bonavita Metropolitan coffee maker hinges on two things: How much you're willing to spend and how fast you drink your joe. If you tend to linger over one batch of drip all morning, then this appliance is the wrong choice. Its glass carafe cools too quickly for that. You'd be better off saving up for a thermal-carafe equipped $190or even a $300 .
Those who don't want to blow that amount of cash should strongly consider this coffee maker, though. It makes outstanding drip, automatically, and for a reasonable price. The Metropolitan also has few parts to clean and is a snap to operate. That's enough to put it on anyone's short list.