so straightforward a problem/as straightforward a problem/such a straightforward problem

[Vladv1]

It's not quite so straightforward a problem as it might at first seem/ It is not quite as straightforward a problem as it might at first seem/ It is not such a straightforward problem as it might at first seem.
Are these examples of mine correct and do the mean the same?

 

[Tarheel]

It's not quite so straightforward a problem as it might at first seem/ It is not quite as straightforward a problem as it might at first seem/ It is not such a straightforward problem as it might at first seem.
Are these examples of mine correct and do theY mean the same?

They're OK. However, I would probably say: "It's not as straightforward as it might seem."