Ant. Despite Galen doing the exact same thing in regards to Sidious I don't make claims like Galen >= Sidious. I suggest that somebody could take that position based on the evidence not contradicting it but I in no way endorse someone actually doing so. Like, you not only seem to be doing so on another forum but you yourself are adopting the position as well.
One is a single blast from Vitiate who had a few seconds to gather enough power to instantly overwhelm Revan with the latter being unable to do anything to defend himself. The other was Sidious trying to utterly annihilate a threat to his plans ( Kota ) with lightning and Galen stepping in and reducing the lightning to levels that caused him pain which he was able to do for an extended period after he had already expended massive amounts of energy reserves fighting through Imperial forces and defeating Vader.
This isn't even taking account the difference in power between Sidious nearly 2 decades after RotS having absorbed the life force of billions for that span of time in comparison to Vitiate.
You're right in that there's an unprecedented difference at least.