So that gives me a reason to come back and post, been awhile.

PSP version, normal difficulty. My final score: 387,400 Got partway through stage 2 on the 2nd loop.

One reason I was finally able to do this was because me and one of my best friends were having a Gradius score competition all last week. Late into it, I had 246,600 and he got 1,100 more than me 6 hours before our Sunday 12am deadline so I pushed myself in a marathon session to improve at keeping my options through stage 4, then went on to stage 5 which is a pushover then played it careful on the base. Got to the last room before Zelos before I finally lost my powerups. Had to start over at the checkpoint, but kept my cool, took out the first two duck tanks on the floor, grabbed a speed up and then chilled on the floor under the floating cage and let the other duckors and spinning cannons above me do their thing until I finally got to Mr. Brain himself. Very cool feeling. I sent my friend an e-mail with my score and 1CC details to which he replied, "Wow, looks like I lose this round then" (because we move to Gradius II this week)
The only slight concern I have though is that since this was the PSP version, even though it took a lot of practice, I'm now wondering if I got off a tiny bit easy? I have always had it set on normal for difficulty (which I assumed was the default arcade setting on the PSP collection) and wait level 1 (which is supposed to be closer to the arcade) but I heard that supposedly the default/normal settings on the Gradius Portable are a bit easier? Or maybe I am wrong because today I've been comparing Youtube video of the last stage running in MAME and the only difference I can see so far is that the trap doors to Zelos' chamber seem to close quite a bit faster in the arcade rev than they do on Gradius Portable. Or do they usually not start to close unless you shoot the arms first?
Well anyways, slight emulation differences aside, I 1CC'd a Gradius game for the first time and it's a cool feeling. This is also my second 1CC ever, my last 1CC was Batsugun in summer 2005.