Only real plus is probably fame. I am pretty sure the top NFL stars are more well known than top MLB stars.If you can be a legit star in either league, baseball seems like a no-brainer. More money, longer career, working brain when you retire, don't have to work out as much, what's not to like?
Yeah, it's possible. Bo Jackson was drafted in the 2nd round out of high school for MLB and 1st overall by the NFL. Bo got drafted twice by NFL teams and 3 times by MLB teams though!