OP, it really depends on your touring habits and what you do in park. If you stop for characters and the like, then it could be beneficial. PhotoPass photographers don't have to worry about things like juggling autograph books, pens, making sure Johnny doesn't leave his coat behind when he goes to see Mickey. So while you are worrying about all that, you might miss that adorable picture of him meeting Mickey for the first time. But Photopass is usually ready to grab that special moment when you might be otherwise distracted.
Yes, they will most definitely take pictures using your camera. However in my experience, they will usually take 3-5 pictures using their camera, and then one using yours. The one picture they take with your camera tends to be a "I was there" photo. A posed picture of your family in front of the castle. But with their pictures they may have you do goofy things, and you may end up with the magic shots.
If you only want that "I was there" photo, and don't want to stop at different photographers, or don't do characters, then it may not be for you. The break even point on the PhotoCD pre-purchase for $119 is about 8 pictures. The break even point on the PhotoPass+ pre-purchase for $149 would be about 10 pictures. So if you think you might end up buying that many, or more, then it may be a good deal. The PP+ is a better deal if you want ride/dining pictures as those you can't take with your own camera. Personally, I like being able to load 100+ different pictures of my DW and I onto my digital frame after our trip. No way I would buy that may, nor would I trust a stranger with my camera that many times on our trip. So in my case, I think it's a good deal.
Does anyone know if the Disney visa Epcot Jmeet and greet pictures will be put on Photo pass plus?
To clarify how PhotoPass+ works, it is just a special PhotoPass card that signifies to the CMs working the ride and dining photo sales that you get your pictures for free. At any other location, it works just like a normal PhotoPass. You can hand it to any photographer in the parks and they will use that to store your pictures.
Since the PhotoPass+ purchase includes the PhotoCD voucher, if you do use other PhotoPass cards, all the pictures will be included. The PhotoCD voucher will get you a CD that included every active picture in your online account. So if you get a new PhotoPass card at the Visa M&G, or maybe your party splits up and someone stops for PhotoPass pictures and gets a new card, all of those will be included as well.