Assuming it's very smooth acceleration, it's just like standing on a 26º slope, feeling slightly heavier than normal. Healthy individuals should have no problem at all in such a situation.
> until you think about it as 50% of your body weight tacked on
That's not how vectors work. It's only 11% extra weight. If its reasonably smooth, that's easy walking.
> unsure if that is a constant or if that is simply right at the very beginning.
If the top speed is 700mph then you'd have 142 seconds of 0.5 g acceleration to get to top speed. How often you'd be accelerating or decelerating would depend on how many intermediate stations there are.
I've only had time to skim the full PDF, but there's something about experiencing 0.5g of acceleration - unsure if that is a constant or if that is simply right at the very beginning.
If you're going to experience 0.5g of acceleration over a prolonged period, letting passengers get up and move about is going to be a bad idea. It also doesn't look like there's enough roof to get about in that capsule. 0.5g doesn't sound like a lot until you think about it as 50% of your body weight tacked on, in a direction you're not used to having it tacked on. Pretty simple in a seat, much less simple trying to walk.