You will be lucky to see 6th stage in God of Game unless you have skills. It's pretty hectic. I try to zip around, alternating speed, but I often make a stupid mistake and crash into something because the screen is so chaotic.
I took your advice and set it to Hard Human (but couldn't for the life of me get the harder difficulty code to work), and made it to level 5, lost a life and ran into the checkpoint underpowered wall. Now, I did make it through to the bubble stage, but I kept asking myself "am I having fun?", and the answer was no, no way. At that point it started to feel like a chore. The pacing in BL is just horrible, and the sights and sounds are not enough to keep me going to the point of mastering the game (but I did want to see those pretty bubbles!).
I can understand why others enjoy it more than I do, as I do find the weapon system interesting and which gives the game a sense of freedom, but the games pacing is just off for me and it generally feels dull. I mentioned Lords of Thunder before, and that is a game with perfect pacing and balance. For other examples, outside the Turbo world, I think games like Thunder Force III, DoDonPachi and Ketsui get the balance between length, difficulty and interesting level design just right (and something like Mega Man 2, outside the shooter realm).
In any case, thanks for the suggestion; it was fun playing that game again after all these years!