I miss the days leveling roulette gave 1.5 levels... in the 70s, it's more like 1/3 - 1/2 of a level. XD

That being said, I'd have to run the numbers as well - I believe, however, that you're right in that it's less, since (if I'm remembering correctly) normally the bonus scales with difference between your level and the instance you get, and I'm not sure if it accounts for EXP from trash packs. I don't think it's a gigantic difference, however, so it's really not a slap in the face. For me, it's more of a relief - quick, in and out, and because of the level difference, big bonus.