My thought is wait for the new iPad Pros to come out and then decide. If rumors hold true we may be seeing reduced physical size and weight with no compromise in screen size or even the release of something in between the current 10.5 and 12.9. Either way, new ipad Pro designs could ease some of your concerns.
Yeah but right now both the 10.5 and 12.9 are $200 off. I can’t justify paying full price for these devices, especially when they are secondary reading devices for me and the 2018 iPad is $299. I’m sure the new ones may be better but if anything they will be at least priced at $650/$800, maybe even more.