X10 seems pretty low. When obtaining SSG, Goku claims he had never felt stronger. Also claiming he didn't think fusion would be enough to beat Beerus. Goku had previously experienced what it was like to be SS Vegito against Buuhan. Some things to ponder:
- If we go with Super Vegito, who showed us power above SS3 Goku while in base. Then 50x that with SS. So that would be > SS3 x 50 = SS1 Vegito. SS3 is a 400x multiplier. Since Vegito was already above this in base, you get him having that multiplier times his SS and get a Super Vegito/fusion multiplier of >400 x 50 = >20,000x. Fusion be broken. This also doesn't include a hypothetical SS3 Vegito. Yet Goku felt SSG was stronger.
- If you go by Vados' statement that fusion was, "The sum of their parts, multiplied tens of times". You would get (A + B) 20-90=Fusion Power. This would add Goku and Vegeta's power together, then multiply by "tens of times"/a number between 20 and 90 to fit in line with what Vados said. So fusion would be a multiplier of 40x on the low end and 180x on the top end. Or 110 averaged and this would only be the base of the fusion. Then multiplied more by SS forms. Which Vegito has SS1 for sure and potentially up to SS3 at his disposal. Resulting in an average boost of 5,500x for SS1, 11,000x for SS2, and 44,000x for SS3.
- Going by feats, as a SS3, Goku was comparable to Kid Buu who busted planets with ease and in the anime was shown destroying a galaxy over time. In BoG, Beerus and Goku are stated to have jumped up to universal power within their strikes with each other. Our universe contains as many as 2 trillion galaxies. The jump from, slowly, galaxy busting to universal is unquantifiably massive.
According to Goku the SSG multiplier should be massive. Feats, statements, etc. point to SSG being a huge boost in power. If Kefla gets the SSG that Goku did, she wins. If it's 10x she gets rinsed.