Are 529 bonuses churnable?

[Morning Glory]

Hi,
I recently saw a post on DOC about 529 plans offering sign up bonuses. The terms are something like open the account and contribute $200 and then they will credit the account with another $50, so a 25% return the first year in addition to market gains. This can be done for each parent/kid combo. The fund fees for one I looked at are about the same as I am paying at Vanguard now.

 I already have 529s at Vanguard for my kids and was planning to contribute a total of $3k this year (maximum state tax deduction). My state gives the deduction for contributing to any state's plan. My question is whether it is possible to open multiple accounts for sign up bonuses, transfer the funds to Vanguard, rinse and repeat?

[Chrissy]

I didn't even know there was such a thing as a 529 sign-up bonus.  I suppose they're churn-able, but you'd have to either maintain multiple accounts or do transfers to consolidate.  Might be more hassle than it's worth.

[EricEng]

Too many hours sunk opening, transferring, and closing an account for $25.  I have lots of checking, savings, and money market accounts offering $500 that I don't bother with.