skylark - get one. Personally I’m a fan of simplicity, so I wouldn’t bother. However, for similar reasons, and the additional benefit to keep the machine’s shower screen and 3 way solenoid valve cleaner, I think it’s worth it.
Do remember puck screens take some space, and will need period cleaning themselves. So weekly or by-weekly soak them in Puly, and always rinse after each use.
For me, dosing 18g in a 18g basket (e.g: VST, E&B 24h) and putting the screen on top was preventing me from locking the PF correctly. So, I bought the next size up basket 20g and all is well again.
There’s no need to spend a fortune either. I got mine from Amazon and paid £6. You can get cheaper from AliExpress, specially worthwhile considering if you are buying a few of them.