That flare attack is easier if you don't safespot it. But the reason you want to do it is so you get pointblank damage on it and don't have to face its first attack again (And easily keep the MAX bonus).
You'll want to move in right away, the boss usually shoots up one nuke and takes a 'lil break, sometimes shoots even more and you can't get in right away. It's harder on the C type ship obviously.
The boss moves around in anti clockwise circle 2 times and stops shooting. You'll want to move OUT from the safespot the second time it moves down because there's around 75% chance it will shoot while moving downwards meaning you'll die.
As for shot type comparison:
C-S: Easy survival for stage 5 and 6, although C-L is way better for stage 6. Stage 2 and stage 5 are easy for getting the 330HIT for loop2 requirement.
Scoringwise it sux on bosses and you'll probably be bombing some bosses and losing MAX bonuses later stages. Also with -S type you can't
pointblank the 3rd boss in the beginning.
A-L, B-L: Easy time till stage 5 from when on you'll need to plan your moves and redirect bullets well. Easytime getting 270/310HIT for loop2 requirement in stage 2, I'd suggest learning the route that doesn't get all the bees unless you plan on beating the WR or something. Both A-L and B-L rapidfire create slowdown in crowded areas and when lots of bullets on screen, not sure if that's a MAME bug.
Scoringwise really good IF you can survive well after stage 4.
I think C-S is good if you just want to play the game to clear the first loop and not care for anything else like score or 2nd loop. Otherwise I'd go with A-L, B-L or C-L (Sacrifice speed for side shot when going from A to C).
Also just so everyone knows:
P1 Side: Using a focused bomb (The laser bomb) when you have your MAX bomb bonus on will NOT cancel your chain, useful in stage 5 and 6.
P2 Side: End of stage star bonuses or whatever stack after each level, tiny boost in score.
