[dragonwriter]

> Your C corp technically has to buy that IP from your LLC - which cost something.

It doesn't have to, but until it does it doesn't own it and can't enforce it. The former LLC owner may own the IP as the successor in interest of the LLC, but even if they were the sole stockholder of the C Corp, that wouldn't give the C Corp any rights at all (it might use the IP because the owner had no interest in enforcing rights against the corp he owns, but that's a tenuous prospect and a dangerous one for other investors.)

> Definitely talk with a professional to make sure you are taking appropriate steps in transferring the IP.

Definitely this, in any case.