One thing I would like to see in S1 is at least the possibility to get away from the "my first routing" structure and let us route anything to anywhere. For instance I like to create a send on an delay FX bus back to itself, turn the feedback of the delay low, and then I can put other FX (reverb, disto etc) in the feedback loop, and automate the self routed bus for feedback...The splitter is nice in S1, but sometimes I would prefer to have two busses for parallel FX, and so on.
An easy way to do this that would make it relatively safe for the newbies who are at risk of making feedback loops, would be to make a "bus source" plugin, that simply lets you select which bus or send you want routed to the channel it's on, and a mix of the plugin's input and that bus/send FX levels. This would even work with sidechain key listen if S1 didn't block the self routings.