I have used the La Pavoni Europiccola for quite a while, I think I am capable top make consistence coffee out of it.
But the real test is using an open bottom portafilter to make the coffee. If I did anything wrong, the open bottom portafilter will let me know clearly.
Finally, I decided to buy this bottomless protafilter (recommeded by John)
Expensive? Yes. Very expensive.
But since I don't wanna cut the original portafilter, so I have to spend more to buy one extra.
The finishing is excellent. This also serves as a two spout portafilter, all you have to do is to screw back the bottom plate and double spouts.
Result, a few shots tell me the distribution of grinds require correction and that's it, making delicious coffee is even more easier than before.
Not a must for goods coffee, but recommended.