I have not bought either of these passes, but have used several others in several countries. I make a list of the sites I want to see, then go to their websites to get the admission cost. I total these and compare it to the price of the passes available. If the pass will save me money, then I buy. If I will break even or pay slightly more for the pass, but save time such as with skip-the-line features, I will buy. If you have the pass you will also probably see more, because you might not go into a small sight if you have to pay an admission, but if it is "free" with the card, you may go in for a short visit.
I have a pass question of my own. I have the 72 hour Omnia + Roma Pass for Rome. It came with two separate cards. I think that they are independent, but am not sure as the literature with the card and on the website is not explicit. I think that the Omnia card is used for the Cristiana hop-on-hop-off bus and Vatican sites only and that the Roma Pass is for museums such as the Coliseum and public transportation only. That would mean that they have their own 3 day time periods that do not have to run simultaneously. Am I correct? Also, it is called a 72 hour card, but it appears to be a 3 calendar day card. Am I correct on this issue as well?