The horsepower rating of a door opener is a sales gimmick. If the door is properly maintained the smallest opener will work with no problems. I have a 1/3 horsepower opener on my garage door and have no problems whatsoever. I do maintain the door and opener though. 99% of all openers sold are 1/2 horsepower.

So, you're saying 3/4 HP is not too strong, right. I found this craftsman model for a good price ($165), so I just want to make sure I'm not going to damage the door by maybe opening it too quickly.

if set properly, it will never damage it. the only advantage the 3/4hp has over a 1/2hp is it MAY open/close the door a second quicker.

i recently replaced one of my openers, and after much discussion with folks in the know i just put a 1/2 back in. the new 1/2hp opens/closes slightly quicker than my other old one of the same model.

the only time you could damage the door would be if you set the up/down force too high and the door hung on something. even then it would more likely cause damage to the opener than the door, IF it is installed properly in all other aspects.

If you're worried about noise and such, I'd HIGHLY recommend the Wayne-Dalton iDrive. This mounts on the wall and I'd definitely say it's MUCH quieter than any other opener out there. As for speed, it's not that fast because it hesitates when it opens. This is so it doesn't go to fast, so you wouldn't have to worry about your garage door being broken. This of course is assuming you have a sectional garage door opener.