In my point of view, there have been 2 major problems with approaching this topic that have yet to be let go of to this day:
1) The notion that the level he was at for the 10 day wait is the same level he fought Cell at. This viewpoint has been mostly abandoned, but if I understand his argument correctly, Pakl uses this logic to determine Warm-up Goku's level. This is almost as silly as the "he stayed at 50% for 10 days so that's what he used against Cell" argument that was commonplace years ago, in my opinion.
2) Goku visibly powering up. It is important to note that when Goku powered up at Karin's, he was intending to show off his full power. It is also important to note that he started "powering up" from his "resting state." The conclusion that he "has to power up to reach 50%" cannot be drawn from this scene alone. Know why? Because then I can use the scene to argue that he has to "power up" to reach the same level as fucking SSG2 Vegeta.
This isn't even getting into the fact that powering up is only ever used when Toriyama wants to make a big show of someone's power. It's only ever a talking point for this topic, you ever notice that? There are several instances in the Boo arc of Saiyans powering up to full without "powering up" and no one bats an eye, for example. This point, in particular, is what seals the deal, and on a sidenote, this post is proof that my writing habits have not improved at all because I should've mentioned this point first.