Has anyone had experience with reusable Nespresso pixie capsules (similar concept to the Keurig capsules that you can fill/refill with ground coffee)?
If so, Is the flavor and crema similar? Does the grind matter? Any other tips?
I used empty capsules to fill my own coffee and brew it using a Nespresso machine. I would say the result largely depends on the coffee you use, but not the capsules itself. It takes several tries until you get the right amount of coffee into one capsule (I had to stuff one brand of coffee quite tight to get a crema at all), and the amount differs very much from coffee to coffee. Of course, the grind matters a lot, but you can compensate with the amount of coffee.
The only problem I had with the capsules is that sometimes they got stuck when discharging, but you can usually fiddle them out using a fork or so.
I have found 'pixie' (classic) capsule to act poorly for re-use. I have found better results by re-using vertuo-line capsules.
The vertuo capsules are larger, and easier to introduce the correct amount of ground coffee for the process to work correctly. Moreover, I have been able to produce consistent velvety crema. My experience is a couple hundred test 'shots' made.