If you get the early bump you'll still earn all the bonus points as if you were PLT all along instead of just Silver. That is close to 40K RDMs, I believe based on 50% -> 125% bonus change and flying 50K more miles to get from silver to platinum.
They were willing to bump my wife up a couple of years ago when it was the week of the non-refundable ticket that was going to put her over the top. I doubt that they would do it based on purchasing a bunch of refundable F tix, but you never know.
S.