1230U (or maybe even down to 1210U) could be a great option with >14h Wifi@150nits and >10h Wifi@MaxBrightness battery life, given earlier tests of other devices. This presumes no fan or good fan management so that usually the tablet would be silent.
6600U or 6800U would be great alternatives but Mircosoft may have the same problem as most manufacturers: no access to these chips. They are so great that AMD does everything to prevent their use;)
No idea what MS is trying to achieve. They just update the basic specs of the Surface series without any proper improvement on other fronts. They could've put a small battery inside the keyboard by now to make it work detached, which makes a huge difference during many inking applications...that's just one of many potential improvements. This looks like a(nother) 2015 device with updated but mediocre specs. And don't forget how everything is perpetually overpriced year after year.
According to reports, Microsoft is preparing to launch a next-generation Surface Pro device. With ARM and Intel versions planned, Microsoft will reputedly release the Surface Pro 9 or Surface Pro 10 as a Surface Pro 8 and Surface Pro X successor.