I am sure that I will have people disagree, but to me the larger plane is much easier to thermal and have longer flights more days than not. That is not to say that you can't stay up as long with the smaller wingspan, on the right day it feels like a brick will thermal. I guess the best way to put it is I have had longer flight with my 115" Bird of Time, than I have ever had with any of my two meter planes. It just seems that I find lift better and more consitantly with the larger span planes.
The 2 meter stuff tends to be more forgiving in tighter fields, they also do not require as strong a launch to acheive the same altitude.
Sorry I just saw the electric motor part of your question. With the assist of the electric motor you are able to get to the altitude where thermals are a little more forgiving. Down low they tend to make you work harder for them than up higher.
Having said all of that...
I only fly gliders with no electric assist. I am sure that someone will have some experience with those to ad to my ramblings.
Welcome and have fun!