Perhaps. Perhaps not. Palpatine was never in a situation where he needed to use a Force Storm in a duel. It is very possible that it simply was too powerful to be used in close-quarters combat; or perhaps he simply never required to do it. Make no mistake. All of Palpatine's battles in Dark Empire, he won. He won them without much difficulty, and even as he was dying, he managed to defeat many a Jedi in battle.Revan is an anomaly. You have only accounts of people who describe his power. You do not, for example, know if Palpatine could've defeated the Echani or not. I do not know, and neither does anyone else on the planet, save for Lucas. Then, you have Malak and Bandon. Either two would have extreme difficulty with ROTS Sidious or Dooku; and Dark Empire Sidious could take and crush Dooku, Yoda, or Mace in combat. So far, there have been no objections to this rather saddening revelations. Even the most anti-Sidious person will sooner or later have to realize that he is FAR beyond any PT Jedi or Sith Lord in his Dark Empire persona.
Revan's powers haven't gone into detail. I could argue, for example, the feat that is known as 'Force Storm' in the KOTOR games is legitimate. And if it is, then I am sorry to say that Revan's Force Storm pales in comparison to Sidious's own. It is not, even, a fraction of the magnitude that DE Sidious could summon. And, also, perhaps Sidious could mold the Force Storm into a smaller varient, yet still very deadly, and use it in melee combat. Who's to say?
You have in-game experience to argue. Which can also be quelled with the simple understanding that in-game battles with KOTOR are video game. When Revan is slashed with a saber in KOTOR, a limb is not removed. Nor does he die instantly. No one does, in fact. It is video-game over-exaggeration, which I agree with. If, in a Star Wars video game, one slash of a saber will kill you, it doesn't seem that fun. But for all intents and purposes, in-game knowledge is nullified instantly when using it in a hypothetical duel situation.
Then, you have accounts from individuals such as Malak, Kreia, and Republic soldiers. There is a very possible chance that they are telling the truth. But as for the Republic soldiers, all they heard were 'rumors'. If I recall, pf those who battled Revan, few lived to tell the tale. So again, it's mainly rumors.
- Kreia. Kreia describes to him as 'the heart of the Force'. Now, she could've been using hyperbole to describe him. Or, she could've just been saying the truth. But also think. Kreia hasn't seen a Ragnos or a Nadd, nor is it likely that she battled Kun. So, perhaps she simply saw the most powerful Force user (Revan), other than herself, and saw the immensity of his power, and assumed he was the closest thing to a 'Force-god' she's seen. But, it might be possible she would've changed her tune, should she have ever gazed upon DE Sidious or Yoda or NJO Luke.
Now. As we have seen, in Dark Empire, Sidious ranks up with the best of them in power. Bane could NOT defeat him. Neither could Malak. Neither could Kreia. And so on and so forth. But, Revan is an anomaly, and all we know as of yet to describe him are second-hand accounts from NPCs.
It is possible that he is stronger.
But judging from what we know now, Revan could NOT defeat Sidious in a duel with a saber or with the Force.
But this is subject to change.