I've picked this up again today after a break and have been able to drop my previous habit of being trigger happy on powerup, largely because I can raise the counter much quicker now just through better familiar control. Suicide bullets + actually moving the familiar to the left when left shooting=speedy counter. The best example is that on the first stage my score was previously varying between 50m and 130m. Not only can I now get the first points extend (200m) on the first stage consistently, I've managed 320m so far. However my survival performance has tanked, possibly due to the break, possibly just me having an off day. So while my scoring is improving, I'm not getting far enough. Admittedly that's a decent compromise, but I was getting to stage 5 regularly before.
I gave the EX a go on a early run, I didn't have enough health to bother challenging the last boss and my score was pretty pathetic so I figured why not. I made a stupid mistake and lost my last life, but you're right, I got 500m pretty much unchallenged.
My all clear was 1.54b, my previous high was 2b on Satan Claws. I now have a 2.1b on Stage 5 - pretty much two levels less required to get 95m more. With consistent play I should be able to make 3-3.5b just by removing some of the mistakes I've managed to pick up. Field C is still killing my score as much as it's raising it, two hits are probably costing me half a billion despite the quickness at which the counter can be filled.
I'm still a long way off that 5b mark