So I recently bought a bottomless portafilter to properly evaluate my shots, and a weird thing I noticed was that with the exact same grind, prep, etc, I get weird channeling and drips all over the place in my triple basket whereas I'd have perfect results in the double that game with the Bezzera PF. I'll go 18g for the double, but boost it to 20g in the triple.

Should I be altering my grind weight or anything like that with a triple basket compared to a double?

Normally you have to coarsen the grind when dosing higher in order to maintain the same flow rate you had with the lower dose. If you don't, the higher dose shot will run too slow. How long does it take for the triple shot to produce the target beverage weight? It should run in about the same time as the double shot.

Sounds like the drips you're getting are from the grind being too fine, but the channeling is probably caused by the puck hitting the shower screen (i.e., too much coffee in the "triple" basket) or distribution problems. Try the nickel test to see if there's too much coffee in the basket. Also try WDT to improve the distribution. Plenty of posts here on both those techniques.

From what I read, VST precision baskets have been designed such that at a given grind setting changing from a double to a triple basket and filling each at its rated dose should get you the target quantity of your drink at the same brew ratio at the same extraction time. if one of the baskets you are comparing is the stock basket, this is very probably not true in your case, so you will most lijely have to figure out a dose and grind that work for each basket individually.

The double is what came with the Bezzera, and the triple is the basket that came with the bottomless portafilter.

I tried the double basket again this morning with WDT and pulled a perfect shot. I even tightened up the flow a little bit to extract more flavour out of the beans and the result was exactly what I expected. Pulled a little bit harder (9.2 BAR or so) and still took a ~30 second shot.

I'm thinking that if I wanted to end up doing the same for the triple, I'd need to get one of these VST baskets. I don't want to be constantly switching back and forth from my grind settings to suit both sized baskets.

The triple basket is inherently more difficult to consistently distribute and tamp than smaller baskets. The VST 18g basket seems (to me) to hit the sweet spot.

Jack

Is the VST basket a slam dunk better option than just a regular basket? I haven't done much research into them

I'm not sure what you mean by "a regular basket". Compared to my stock, ridged, 14g (?) basket, yes. More challenging, but better. Compared to the ridged generic 20g (?) basket that came with my bottomless portafilter, yes. The 18g VST is less challenging, more consistent.

Jack