I was recently out casting my Xi-2 10 Wt & my new to me 9/10 wt Atlantis with a outbound Intermediate line. Trying to do a comparison to answer this very question. I could defiantly cast the two hander farther with less effort than the ten wt using the same line. Both rods load good with this line.
However I am not all that great of a caster yet. I am good for about 70 ft or so with the single hander. I can cast the two hander about a hundred feet. I dunno if this means more power or not.
Right now I am no so concerned with distance as I am just trying to get the timing & mechanics down to a consistent level & work on my tracking & acceleration to a crisp stop.
I do find with either rod, if I get everything right they shoot line like no tomorrow and no effort on my part. Just like Adrian & Juro do on every cast They make it look so easy.