Not really complaining about the hitbox lol I do realize you are not aiming for Touhou; for the hitbox it just took me a while to get used to was all (since y'know... Bullet Hell games I play usually have really tiny hitboxes). I do think it fits your game well with the amount of bullets on screen
Hey that Devtober project sounds cool.
Just make sure precise control is possible the next time you make a SHMUP. Slippery control is very, very uncomfortable when playing SHMUP games -- and the more bullets there are the more necessary precise control is.
I think if you check the controls of the more normal 90s SHMUP games like Strikers 1945 (II), Raiden (I played Raiden II), G-Darius, Raptor CotS, etc., their movement schemes are usually either instantaneous speed (i.e. pressing a direction instantly gives you a certain speed) or at least very high acceleration/decceleration (from what I remember).
For further reference Touhou's (...which technically is a 90s SHMUP game since the less well known earlier games were released since 1996) control scheme is instantaneous but it has got a "focus" button for moving slowly for more precise dodging :P