Edit: Live View has problems in the beta as well.
I did get the failure condition to happen again. I took a sequence, and attempted to switch to live view after it finished and it failed again. The log shows this:
[5/17/2016 12:18:14 PM] [DEBUG] [Camera Thread] SGM_FRAME_AND_FOCUS message received...
[5/17/2016 12:18:14 PM] [DEBUG] [Camera Thread] EOS camera: frame and focus...
[5/17/2016 12:18:14 PM] [DEBUG] [Camera Thread] Canon: Setting ISO to: 25600
[5/17/2016 12:18:14 PM] [DEBUG] [Camera Thread] Canon: ISO look val: 136
[5/17/2016 12:18:16 PM] [DEBUG] [Camera Thread] Error in Frame and Focus (Canon): Value cannot be null.
Parameter name: source
Now, I cannot even use live view when I freshly open SGP, even after a reboot, except for when I am on WiFi, then it seems to work provided I do not attempt to run a sequence before I use Live View.
As for image download time, the notification system was where mine was lagging. Once I disabled that, I got speeds comparable to other software programs. The notification system is not something I would personally use, so I do not plan to buy that module. The framing and mosaic wizard on the other hand, has me interested. I am going to try and use the normal plate solving though, via the control panel, to see how well it works compared to Astrotortilla.
I tested CR2 mode and RAW mode and there was no difference in the two in terms of speed. I am seeing 8-9 second downloads over WiFi based on what the log says, like:
[5/17/2016 12:05:19 PM] [DEBUG] [Canon Download Thread] --------------> getCapturedItem time: 8827 ms
USB tests show 2000-2500 ms download times.