Experience bonus from line >50 exp

Is it known what % experience bonus is given when a less experienced player is a line with a >50 average lineup?

I'm currently trying to decide if picking up an older experienced player that i won't use long term is worthwhile to sling my current squad up until they're all 50, or if the experience lost into having that older player on scuttles the idea. I can currently jumble my lines around so 3~4 players are benefiting at a time.