Yeah, posts on 2Ch. But they were detailed, discussing aspects of the runs, how to maintain a manageable rank, etc, so I'm inclined to believe them.
There was a time in 2006 when a lot of posters there really took a stance against the infinite lives "bug" (as they called it), and worked together to discuss strats on how to beat the game with a high score w/out the infinite lives. There is a lot of great info there, and I've posted most of the juicy tidbits in previous pages of this thread.
Remember, just because you can't do something, doesn't mean some wickedly talented dude in Japan can't.

But as I've said before, it seems like clearing this game with full scoring without the infinite lives is on par with a DDPDOJ 2-ALL, in terms of difficulty. How many westerners have done that? Zero. No one even close really.
BTW the guy who got the non-infinite lives 10mi ALL with M&M is the one who stated Extended mode was impossible without the Infinite lives, so he gave up on the non-infinite lives (and I think the whole game) after that. He got to stage 2-1 in Extended (w/out infinite lives) and said the rank was so bad it was a complete joke.