Just to note the ICE's are rarely that busy on second class either, except at peak hours - when I've used the twin pass have only had it happen once on a routing of a packed train (only on one segment of it , was taking it north to south, like 5 hours)

And the twin pass is quite cost effective indeed vs point to point (in Germany). Although if you're planning to stay within one province there are regional passes in some which are cheaper (non-ICE though)