We have had an Opal One pod machine for a couple of years which doesn’t get much use nowadays. Have tried a few speciality roasters for pods but nobody comes close to Colonna (at least from the ones I’ve tried). They have a few options at a time including some fantastic ‘rare’ options if you’re a fan of lighter but not too underdeveloped roasts. I would say, they get a bit lost in milk though of that’s your preference. I stick to an espresso (~25mL) or longer black (80-90 mL) drinks…. The latter coming at just about filter strength. The wife did like the Colonna decaf in milk though.
The Opal One gets round the issues you mention with grounds getting into the system @MWJB. See Hoffman’s recent video explaining this:
