Dooku pulled an elaborated escape plan off, or he would have been cut into pieces sooner or later. The very same faith would await Sidious, if he where to face Yoda on equal ground.
At least in film Yoda's and Dooku's fight is pretty even. Both script and book, if I remember correctly, confirm that Dooku got tired and slowed down. And Yoda failed to outskill or outspeed even tired Dooku. I don't see how Yoda can wear out Sidious, who has much greater Force reserves than Dooku.
Also, unlike Dooku, Sidious is confirmed to be level 9 combatant like Yoda, which means that the outcome of their fight will be based on circumstances and plain luck. So you have no basis to claim that Sidious would be sooner or later cut into pieces on even ground.
On contrary I have the basis to claim that Sidious is more likely to win on even ground:
"He's better than Yoda in a way because he has the extra power of the dark side," Gillard explains. "His character is so shrouded that his fighting style should be shrouded as well. The Emperor is deadly dangerous."- Nick Gillard
They are both fighting on a confined space. That one of them either choses or is forced to fight on less of that space than his opponent is irrelevant to that fact. Sidious could have utilized the sides of the podium, just as Yoda did. But either he didn't want to do so, because the advantages the middles position offered to him. Or he was forced to stay in that middle position, because Yoda was the superior fighter.
You don't take into account their size difference. Yoda is much smaller, so for him the same platform offers more space.
Moreover, Yoda is plainly far more agile, which gives him far more options on confined/uneven space. Other characters clearly can't jump around the way Yoda does. Anakin tried, lost all his limbs as result.