External Monitor support will happen in some capacity according to F(x) answers to IGG comments and discussions i followed. In question is if the same method like on Pro¹ can be used since usb 3.1 hdmi video out is not officially documented in sd662 specs. Community hope is currently that F(x) knows better and the feature is just undocumented (for marketing reasons?) but still available.

In daily use you might much more profit from the 20-30% less power consumption of the sd662 imo.
Benchmarks say it can be up to 20-30% slower then 835 but that still means "same" compute power per watt

Some games might give lower fps.
My Phantasy is not vivid enough to come up with what android users do on their device nowadays, maybe video editing to max out the cores?
For sfos kabouik remarked that it might have an impact on performance in containers where the 835 really shines currently. But that is to be seen.