I notice much nicer crema with the bottomless PFs, and use them for milk drinks. However, shots from my splitter seem much sweeter and more developed, I generally prefer them. A friend who has judged USBC in the past always recounts this one B who poured his singles into a vessel, (glass shotglasses, if i remember), THEN Into the demitasses that he served. He says it was like candy, and far and away the best spro' he had that day.
That being said, I only REALLY learned what I was doing until I could see what was happening during the course of extraction, and it was happening so quickly. I would dose and tamp, having an idea of where problems might occur when I engaged the pump, and get to see the results within seconds. Immediate gratification. Adjust, corrrect the problem, try again. Highly reccommended. Here is the only issue:
Trading taste and aroma perception for the visual. I am the trainer at the shop where I work, and I dug out the Nakeds a few days after I started, all of a sudden alot more coffee started going down the drain. If the Bs were not enchanted by the aesthetics of the bloom, they would'nt drink it. None of them are experienced enough to know exactly what that shot is going to taste like by what it looks like. They will make a latte for themselves, and go through 6 or 7 shots, till they get one they like the 'looks' of. I encourage them strongly to taste everything they decide to pitch, but I can not pour spro' down their throats. Just a word of caution. The proof is in the puddin'.