I'd have to agree. Its hard to compare relative gods but...
Usually I feel Dr. Strange has a harder time fighting Shuma than Dormammu... so I'd say using Dr. Strange as a barometer...
Shuma wins 1 and win and loses two only cause he'd be probably weaker in Dormammus realm... and Dormammu stronger.
__________________ Quotes from Hia8:
"I claimed that the science is sometimes faulty."
"You don't understand. This is fiction. That means none of this stuff really happened."
"There is no writer to purposely ignore a character's natural ability just because it suits the story."
"in some cases because the writer knows that Character A will dominate Character B easily and refuses to allow this to happen for the sake of the story."