We did Helios, it is nice for a quick break (we went back to the room yesterday during the rain storm and waited it out from our theme park view). With that said, I'd argue it's a disadvantage during early entry. Until you get to Super Marioworld, everyone from the front is already in. If they keep opening up Battle at the Ministry with early entry though, then you have the advantage. We did one day entering Mario world and it was kind of a bust (mine kart was down - seems to always be down) and bowsers filled up fast (stardust was also down this day, so really it was bowsers or the monster universe rides).
The second day we went for Battle at the Ministry. Two things with this, people from the front, still were beating us from Helios there (they were sprinting - and honestly, Universal needs to shut this down before someone gets hurt or people fight in the morning as we witnessed multiple people get bumped by runners, and also multiple people arguing with each other because their kids sprinted ahead of everyone and then all the adults tried to push through the crowds to catch up to them in the line).
It also seemed like anyone could have entered. I wasn't at the front (so I don't know what it looked like), but to get on all the other rides during early entry and to enter those portals, you had to show your room key. For Harry Potter area, it appeared to be open season and they weren't checking anyones room keys. Now I don't know if they stopped people further up from going that way (maybe someone who has come that way, can tell us), but it seemed like even people without early entry were just running that way to get into that portal.