The issue in my opinion is that a huge amount of standard conversions is pretty easy for the most part and then has a few stupid long 1/8 streams. Even if your pattern and accuracy skills are mediocre, you'd be able to farm lots of pp by getting ridiculous speed values if you can just mash fast enough.
For example, take Kanburisa. The patterns are super simple, but that 400 BPM deathstream lasts forever. A few people can mash fast enough to FC that, but does it mean they could play a regular 270 BPM map? No, absolutely not. Some of them can (Orukaa for example), but the mashing speed nesseccary for Kanburisa and similar maps does not automatically transfer into "real" skill.
If the calculation method for the speed value is even remotely similar to how it is in standard, converted maps will be imbalanced. I don't think they should be completely ignored in pp calculations, but definitely weighted less heavily.
For example, take Kanburisa. The patterns are super simple, but that 400 BPM deathstream lasts forever. A few people can mash fast enough to FC that, but does it mean they could play a regular 270 BPM map? No, absolutely not. Some of them can (Orukaa for example), but the mashing speed nesseccary for Kanburisa and similar maps does not automatically transfer into "real" skill.
If the calculation method for the speed value is even remotely similar to how it is in standard, converted maps will be imbalanced. I don't think they should be completely ignored in pp calculations, but definitely weighted less heavily.