Embolden is a 2m Cooldown, Devotion 3m. Devotion is 5% flat, Embolden 6% average over 20 seconds (but obviously it's more complicated). Embolden only does physical damage and personal, devotion is all damage. And obviously Embolden is 20 seconds, Devotion 15.

Embolden is flat out the better buff unless you're running more than 1 caster DPS right now, and the fact that embolden is still physical only for support is kind of a problem due to how it enforces group composition.

So no, Summoner should not be equivalent to rdm on damage, because smn has vastly lower group utility.