Folks that fly the widebody heavy jets normally earn more, with most airlines.
Certainly as it should be, without a doubt.
And...why not, as these folks are generally more senior within the company.
Depends on the circumstances. It's true that in most airlines the senior guys bid for the widebodies and therefore they tend to be paid a bit more. In my airline, the pay scales are the same for wide and narrow. We operate two types. The widebody is a developement of the earlier narrowbody and consequently the narrowbody is less well developed and is marginally more difficult to operate. Also, the widebody flogs back and forth to the major cities wheras the narrowbody does the same routes but also has the smaller and often more challenging destinations to contend with. So as the narrowbody job is more difficult in my airline, you could argue they should be paid more!
As it happens, the more senior guys tend to favour the widebody for a slightly easier life and they do get paid a little bit more as a function of being on a higher pay increment. But many of us, including myself prefer to stay on the narrowbody for the more interesting flying and fewer nights away. Although I have the seniority for the widebody, I'm not interested in bidding.
I have no problems with size!