I was thinking about Vernal and how to best scale her.
So, we know from Qrow that she was relatively inexperienced with her powers.
However, I think this applies more to her maiden powers, and not the increase in speed, power, and durability.
I think she would still scale to the other maidens in terms of power, speed, and durability. For example, Winter, who just got her maiden powers, went from barely holding on to Cinder to fighting her on equal footing. She relied on her enhanced ice powers and flight to do so. Thus, we can say that she was just as inexperinced, if not more so, then Amber. Yet, again, she manged to match another maiden in combat in seconds after she got the maiden powers.
Qrow states that Raven and him are on equal footing. However, as we see in Raven vs Cinder, Raven is able to, with her maiden amp, match Cinder blow for blow again, this time being MUCH more experienced with her powers.
Even Cinder, who only matched Glynda Goodwitch with her half-maiden powers, got strong enough to kill Ozpin with the maiden buff, who still had Remnants of his old power and, as the headmaster of the school, has to be one of the best.
That's what I mean too. That he can match her in base, but no way in hell would he do so with maiden powers.
And, for as inexperinced as Amber was with her powers, she still managed to use all four elements.
Thus, I feel comfortable in saying that Amber, in theory, can scale to the other maidens. (edited)
It's even more clear with the fact that she probably had them longer then Cinder, Winter, and Penny.