Switching to Outland, from the old world, is a massive experience per hour boost.

I didn't do the massive pulls in Ramps, that I was doing in SM/Strat, but the experience was still good.
My pally is sort of geared, an assortment of iLV 200-245 stuff, mostly badges or BoE's.
I did Ramps in 4-5 pulls.
But did two sets of toons from 55th to 60th, in an afternoon.

Have not tried Underbog with 55th toons.
But I far prefer Ramparts to Strath/Scholo for 55+, its way faster.