I recently bought a pair of Doc's Pro Ear Plugs after I had a rush of cold water give me vertigo. I was messed up for the rest of the day. There are several considerations to be made before you buy them. Do you think you need them? IF you have been diving through different temp layers and depths with zero issues, dont bother with them. If you hate that cold rush, the vertigo, or seem to keep water in your ears for days after you dive, then by all means try them out.
If you are going to buy a pair, make sure that the sales clerk has been trained to help you find the right size. Its not difficult, but if they dont know what they are doing the wrongs plugs wont keep water out or worse they will fall out and then you cant return them. One you get them, practce puting them in. Its simple but they dont fit like regular ear plugs. Mine sit mostly on the outside of my ear and only seat correctly with the water pressure pushing in on them. They do keep 95% of the water out and can make a world of difference when you come out of the water into a strong breeze or the boat starts moving right after you get back on board. they fit relatively comfortably with only a minor amount of irritation. They are also vented like previously mentioned. As you equalize the air can escape through the holes in the silicone. Very littel to no water makes it past these holes.
As for wearing them with a hood, unless just having water in your ears causes you issues, dont combine the two. The hood should keep the water on your ear warm and more or less in place. The hood and plugs by themselves cause a drop in hearing as it is, combining them makes it worse.
I love mine. They have worked very well for me. When I surfaced, my ears were dry and comfortable. I didnt have that rumble in my ears when I bent over or any residual pain afterwards. I dove to 60 feet with them in with no noticeable change in comfort or pressure. I was able to clear descending and equalized just as easily ascending. I only wish I had the ones on the string. I didnt know about those until after I had already bought the regular ones. Also, if they offer a colr other than clear, get them. The clears ones vanish the second you put them down. They do get slightly irritating, but if you just ignore it it eventualy goeas away. Its far less annoying that vertigo or ear infections. Overall I love mine and dont consider the 13 bucks a waste.