I use "live" unwrap mode and "pinned" vertexes in Blender. P to pin, alt P to un-pin . That way you can edit not only a selected loop of UV but rather all others like stretching a pelt . It requires a bit of miss and hit , pin , align ,unpin etc but works better than just standard proportional editing . I think Maya should…
If you want to try pins + live unwrap mode in Blender make sure you marked seams first or did UV>seams from islands . Pin a few points with P , check in "live unwrap" in UV menu , then grab a pinned point and try to move it . After that it's pretty much self explaining . It's not designed to exactly straighten islands but…