Why should the portafilter diameter affect the shot quality so much?
I'm no physicist but how else could it be?
If you exaggerate it and spread the 14G to a thin layer you can imagine that extraction has to taste different from one where the 14G is stacked up in a long skinny column no?
I have the answer you have all been looking for. After owning a ton of machines, many levers both home and commercial, prosumer semi-autos and commercial semi autos, I have done a lot of research into different companies takes on PF size.
Both a 58mm double commercial PF basket and an Elektra MCaL or Olympia Cremina (spring loaded vs manual lever. . . that calls for a completely different thread of it's own) 49mm double PF hold right around 18g of coffee, but there is one huge difference. . . a 58mm commercial machine will pull a 1.5oz shot while my Elektra would only pull a mere .75-1oz shot with a pull and a half of the lever (aka fellini maneuver). So why the difference in diameter? The narrower baskets give the resultant shot so many more layers of flavor! It is night and day with the exact same coffee. I happen to have had an Isomac Tea II at the same time as the Elektra and they both made great shots, the Elektra's just had a lot more character (The same can be said for the Cremina's shots). This was consistent with almost any coffee I put through both machines.
The Elektra did have a few downfalls of it's own and they are as follows: they can only manage about 3 double shots in a row and they are so hot you need to shut them off, they can only hold enough water for about 5 doubles total with flushing in between, small shot volume, and although their finish is so beautiful (I had a brass and copper one) they were impossible to keep sparkly clean and regardless of what rag you used to clean it you would get micro-scratches!
For the above reasons I got into commercial lever espresso machines. They have huge boilers that can accommodate even the largest group, you can plumb them in or run them from a 5 gallon bottle, they have steam for days, you can leave it on all day without a problem, and if you get a classic one they look sooooo cool! One problem with the majority of commercial lever machines is that the portafilter size bounces back up 58mm. That is why so many lever fanatics drool at the site of new and old La San Marco Lever espresso machines. To this day they maintain the original 55mm portafilter on their commercial levers. This makes them the best of both worlds. You have the convenience of a commercial lever machine with the beautiful layered flavor profile of a smaller home model.
Another thing that really sets levers apart, both home and commercial models, is the overall simplicity and lack of electronic parts. The only electronic parts they have are pressurestats and heating elements (and a brain and PID if you so choose). To me fewer electronic parts means fewer problems, and this has been my exact experience. I have never had anything break on any of the levers I have owned whether I purchased them new or purchased them used and rebuilt / restored them. Obviously you will have to descale them and replace their o-rings from time to time, but that goes for any espresso machine.
No matter how long it takes me I will convert some of you
! It sounds like a few of you may be converting yourselves. . . . Lever machines definitely have a steep learning curve. You will not set one up and pull an amazing shot straight away, but that makes pulling a great shot so much more exciting. Once you get use to them and their borderline finicky tendencies you are rewarded with outstanding espresso.
