This is awesome! I’ve updated both my A4 and AR MKII 
Fooling around with the random param on the SRC page of the AR tracks is delicious. I don’t think that it’s possible to record random pages on the fly, is it on digi boxes?
The scale per track is something I’ve wanted forever on these two boxes
(on the AR for 2x or 3/4, on the A4 for longer sequences). Makes me very happy.
BPM per pattern! I’ve been using the OT for that in the past but using any of the two analog boxes as MIDI master is a thing I always wanted.
The new UX is also very nice. I really like the new SAMPLE page on the AR. 
And last but not least MIDI sequencing! I’ve been regretting selling my Octatrack because MIDI sequencing was so good (LFOs, ARP, life-recording CCs, mangling, etc.) and I don’t have other hardware sequencer. Now this is not a replacement for what the OT is capable of but opens new ways to work with external gear.
I’ve got a Minitaur and a MS-20M and I’ve been using all 4 CV outputs to trigger GATE/PITCH on both synths. Now I can sequence both via MIDI and use 2 CV for each synth or 4 for a single synth. 
With the AR, layering samples on top of a controlled external synth (with matching pitch) is now a thing! 
This update is huge! Thanks to all the people involved 
Now, an extra page for a few MIDI CC params would have been amazing. I’d also prefer to have a selectable MIDI machine (with CC params, LFOs) instead of the current workflow implementation of sending MIDI notes in addition to the current sound.
Also, in order to use the mini-keyboard (and probably an external MIDI keyboard) with the A4, I have to set the AUTO channel to the wanted MIDI channel. If AUTO is not set correctly, playing live on a track won’t work. This is problematic because if set to the channel of an external synth, it will still trigger MIDI notes when other tracks are selected. When controlling multiple synths, you have to switch MIDI channels in order to preview the sound of each synth. I assume that the same applies to the AR.