You can speedrun all you want to, but your runs won't be accepted to the leaderboards, due to load times being a lot faster than runs on an official disk.

If I were you, I'd try running the game from your HDD, and if you find you enjoy it, pick up a cheap disk so you can submit to the leaderboards.

You can get discs for like $10 online.

You can get discs for like $10 online.

I was browsing through the forum and end up seeing this post. Since the WR is now done w/o loads, could ISO be accepted in the leaderboard? The runner won't have any advantages after all

No, it creates an advantage for runners who do not have sub-25s, and it is still an unofficial release.