I have owned X-E1, X-M1, X-E2 & still own an X-T1.
there was surely an improvement between the X-E1 to the X-E2 but the EVF was not incredibly superior, just better. I would buy a X-E2 if you really like the improved software and characteristics.
Both the X-T10 and the X-T1 handling is vastly improved by a L plate with a front grip. They cost a pittance and they are very useful both for balance or mounting the camera on a tripod.
Owning a couple of batteries is not a luxury that one should be thinking too much about so the solution to this problem is rather simple.
However, and please don’t take this the wrong way, you are saying that you are displeased with shooting for 3-4 hours and yielding 150 pictures as a result.
I understand that nowadays the trend is shooting a lot first and go through thousands of shots to chose from after but there has to be a way to think more and shoot less.
Seriously, when I was very young I was working for a press bureau ( although I was never a real press photographer), and they gave us one roll of +/- 36 shots, we were cutting them to size from large rolls ourselves per event.
An we were expected to bring back the beef.
However, I understand that you may be into weddings.
Those are notorious for asking a lot from the photographer covering the event, but two batteries should be sufficient and in any event (pun) buy 3...!
