Pro: Since you can nominate another steemian to receive a share while you are also buying a share this will help new steemians while also helping yourself.
Con: Sending 1 steem to SBI is not the same as sending a delegation of 1 steem to SBI the steem that you sent will no longer be under your control and also SBI could down power themselves and you would be left with 1% of nothing, again "no control".