So I was playing some different modes today, 1.5 Original again and fiddling around with Black Label Original and Maniac.
The key with scoring in original is really
not dying, the rapid/shot switching is of course going to build your overall meter faster, but getting hit depletes it by 1/3 so a few consecutive mistakes and your score potential is going to get flushed down the toilet.
Maniac on Black Label is an interesting animal. Parts are harder, other parts easier, and your meter builds so absurdly fast compared to 1.5. Your firepower is a combination of the normal/abnormal from 1.5, so you are rather overpowered. Because the counter maxes at 9999 in different parts (and far more frequently) there are more opportunities to cash in for points.
Original Black Label is a hoot, broke 400 mil with several lives remaining after the clear and I wasn't even 'gem shedding' with the pointblank tricks that the pros do. The nuts on shmups score between 2-3 billion in this mode
Some even say it's the mode that has the most potential in difficulty/challenge because of how risky it is to score highly, interesting in theory.
If people playing the port on 360 haven't downloaded Black 'laval" (misspelled in the market place last I saw), you should take the time and do so, it's probably the more popular version.