I did a lot of painting last year with a Wagner power roller. Although some people dislike power rollers, I wouldn't consider using a regular hand roller after my experience:
1) After doing one ceiling, I discovered that I didn't have to bother to lay tarps/plastic sheets down - the power roller's guard prevented drips and spray. End result of painting the ceilings and walls in the living room, dining room, kitchen, and entry hallway ...no drips, none, nil, nada, zip.
2) Painting is very fast with the roller. On the other hand, clean-up takes longer than when using a hand roller.
3) When doing my cathedral ceilings, I had to use a system of ladders. With the power roller, I just went from ladder to ladder and didn't have to mess with moving a tray and risking spillage.
Jean