These are my experiences and opinions only, I've had them all......they all open and close the doors......chain drive noisier, needs maintenence (oiling of chain)....screw drive quieter than chain drive, needs maintenece (oiling screw drive)......Belt drive very quiet, needs no maintenece.....prices rise in the same order as mentioned.....my current drive is a belt drive and I love it and feel I should have done it from the get-go....This model starts slow and then speeds up until the door is almost completely open and then slows down again....same sequence when closing.....very quiet and less abuse on the door hardware. Keep checking your post...Don 1 is very knowledgeable in this area and if you're lucky, he'll see it and comment.

I agree with maryland irisman totally and the only thing I would add is if you are even the least bit handy do the install yourself. The owners manual is set up for the DIY installer and you will learn what all those controls are for. Just take one step at a time. Then file the manual so you can find it when you need it.