CCL: Radical transition state

 Sent to CCL by: "Zach  Taber" []
 My system contains an organic molecule which has a secondary carbon radical
 attacking a double bond. Is it OK to optimize ground state and transition state
 using a 6-31(d) basis set and then run a single point energy calculation at a
 higher level (6-31+G(3df,2p), or similar)? My main concern is if I would be
 missing something for not using a higher level basis set during the optimization
 of ground state and/or transition state. I think it is important to mention that
 I would be using a DFT method such B3PW91 or M06. Thanks