The problem I see with Hepburn romanisation would be having to use "ō" in the non-unicode field. tangorin's style of romanisation avoids this and I believe it is actually closer to osu!'s style of romanisation than Hepburn, but I don't know what it's called.
In a more specific example of HujuniseikouyuuP, I believe there is reason to start romanising it as FujuniseikouyuuP instead. However, this would imply ふじゅに (fujuni) as opposed to ふじゅんい (fujun'i), so there is still the question of we should use apostrophes in these situations, like with ren'ai. Then there's capitalisation. Is it wrong to use FujunIseiKouyuuP to denote the separate parts of the name? And capitalisation issues carry over to many other cases.
In a more specific example of HujuniseikouyuuP, I believe there is reason to start romanising it as FujuniseikouyuuP instead. However, this would imply ふじゅに (fujuni) as opposed to ふじゅんい (fujun'i), so there is still the question of we should use apostrophes in these situations, like with ren'ai. Then there's capitalisation. Is it wrong to use FujunIseiKouyuuP to denote the separate parts of the name? And capitalisation issues carry over to many other cases.