I'm not going to get involved with your dispute with DB, but I think the German Rail Twin Pass (@25% discount) IS the Sit and Save pass. They want people to make reservations during the busy summer season. That's why they are giving the discount on the pass if you do. I saw the "link" immediately, but I approached the discount offer differently. I understand that some people, approaching the offer from another "direction", did not see the link.
Nevertheless, you will have to have a seat reservation any time you board one of the "reservable" trains (ICE, IC, EC, RJ, etc). This will seriously impede your ability to hop on/off, because you will either have to plan your stops and buy reservations in advance, at 4,50€ per hop, or get a new reservation every time you get off for the next hop.
BTW, reservation can be obtained at the time of purchase for up to two specific trains in the same direction. That is, if going from town A to town B, if you knew in advance that you wanted to hop off at town C, for one 4,50€ reservation, you could reserve a seat on the first train from A to C and on a second train, from C to B, but it would have to be for specific trains, and reservations are not exchangeable.