OK sorry my return/result post has taken so long. I actually posted this last night but as I was proofing it we lost power due to high winds. I tell you I almost cried, it was a sweet post about the 18 vs. 21 gram basket. Its tough to re-create art but I'll try.
So... After the Silvia PID install I did try 18 gram portafilter basket. I have to say once you have your dosing/tamping technique down it is difficult to try to simulate channeling and so I wasn't about to try to.
The "Synesso" 18 gram basket is an awesome basket and a great mid-point between a standard 14 gram double baskets and a 21 gram triple basket. I pulled several
double shots using a bottomless portafilter with both the 21, 18 and 14 gram baskets. Did one resist channeling anymore than the standard double? Possibly, that's hard to say. I didn't notice channeling on any of the baskets, as all my shots hit perfect dead center
. Ok maybe one leaned to the side a bit. I think that with the standard 14 gram double there is less room for error in dosing, leveling and tamping. Which is why it may make it a little more difficult to pull perfect shots with.
Here is more of what I observed. The 18 gram had great crema but the 21 gram basket had a bit more crema, I think that could be expected. I've been using a 21 gram basket for quite some time and always pull doubles with it. I prefer both the 18 gram and 21 gram baskets purely for the extra flavor both deliver over a standard. With a 21 gram basket if an espresso is particularly "big" in flavor I will just pull the shot a bit longer. However if with the 18 gram and a rich espresso you could pull the normal shot and not waste the coffee or make it too rich. Personally for me too rich isn't usually a problem.
In conclusion I can't say anything either way about channeling besides try different baskets and see what might work for you. And... I think I am buying a 18 gram basket to add to the arsenal and keep at home on a regular basis. I might even switch over and start using the 18 gram full time.
