I didn't played FO3 before getting TTW so right now I'm playing only at capital wasteland.
I find kind of annoying the mix between (almost lack of) FO3 and (almost only) FNV loading screens.
I think it'd be better that FO3 loading screens appear only in FO3 areas and FNV loading screens appear only in FNV areas, just like the DLCs (you don't get a loading screen from Old World Blues while loading The Lucky 38).
Thanks