Well, I played around with the song mode of the A4 yesterday and sadly it hasn’t the features you wrote (as far as I can see…).
I heard the other machines can do that, so I really hope some features for the songmode will be integrated too. I can live without tempoautomation but patternlength and patternstart would be very usable for the songmode.
Sure one could say if you have two 64 steps patterns (one normal beat and one fill or something), why not break it down in individual 16 step patterns and mix those up but you will run out of patternspace pretty fast in your project (8 patterns instead of 2). I hope Elektron has some plans like this to make the A4 more than just an “addon synth” for the trinity…
I myself can’t afford the other boxes but i really do love working just on the A4 itself so it would be cool to have a better songmode.