"no more complex than" is correct and usable in written English.
You can use it to compare something to a less complex situation. For example, "Setting up this new system shouldn't be any more complex than setting up the old one."
"Maybe we are not any more complex than cellular automata," Dr. Wolfram said, "but the universe is no more complex than us.
Yet, in reality, the supervisors are becoming micro-managers.A member of the Basel committee insists that most of the world's 36,000 banks will be governed by a regime no more complex than Basel 1, in force today.
The other three subcircuits used are no more complex than voltage dividers.
One surgeon said that it was no more complex than sewing back a finger.
We also prove that for every \omega-regular condition, optimal winning strategies are no more complex than almost-sure winning strategies.
We have always been able to feed the world despite various world maladies, sadly we simply choose not to for reasons no more complex than greed.
Of course, a positive no is more complex than simply focusing on yes, because we all are in relationship with one another.
There is nothing simple about the preservation of modern architecture, and there may be no more complex example than the 666 Fifth Avenue building.
A person's capacity for novel-writing and the kinds of thing a novelist writes are surely no more complex or mysterious than a tendency towards jealousy or a reluctance to hug one's siblings.
But in many ways the "good Germans" in a film such as Downfall – a doctor with moral fibre, a gold-hearted Hitler Youth – are no more complex in their saintliness than the evil Germans of the 1940s.
Before Fidyka, no animal more complex than a rat had been subjected to the procedure, which was risky.
