You want to know how this will play out? I'll explain the compromises being made right now, and how I predict it will end.
The new Toomey/Manchin language on background checks will replace the current language, and we will hear about a bi-partisan compromise.
Harry Reid will call for a cloture vote on the bill with the new language. he'll get just enough votes for it.
Reid will then bring up Feinstein's ban on the assault style weapons, and on the high capacity magazines, as amendments with the background check language.
The amendments on the assault style weapons and magazines will fail to pass the votes, allowing Republicans and moderate Dems in gun-friendly states to go home and say that they voted against gun control - and thus, keep their seats in the Senate later. Reid has already planned this.
Finally, Reid will bring the background check language to the floor for a vote. This is to put Senate Republicans that are strongly against the bill in a tough position. It's all political posturing.
Reid will need to get 5 Republicans to side with him, so expect debate. If it passes, it will be by a very thin margin.
Then it heads to the House, and the House Republicans will kill it, thus, wasting our time.
That's your compromise.
Write it down, see how it plays out.