Just playing some Grind Stormer today. Fuckinghell, I am getting my arse absolutely handed to me on a platter here. The enemies are so resilient it takes a real switch in mindset from trying to dominate the screen to dodging and bombing. I really need to git gud here, it's showing me up.
Have you tried the original Japanese version, V-V? It's got the Slap Fight/Gradius powerup system instead of bombs and works quite well. It might even be better balanced.
edit: oh, I just realized you must be referring the the MD version, which has the powerup system anyway. I only played the console version a couple of times, the downgrade from arcade is too brutal.
I've been spending some more time with the MD version of Slap Fight and every time I play it I like it more. The arrange version is a beast, very fun and tough (but not excessively), with a killer OST by none other than Yuzo Koshiro. This track, for example, is very obviously inspired by Gradius: