I'd also never be able to shoot at that angle down without repositioning my lifeline connection or unhooking completely.
I've only ever shot one straight down or at a real sharp angle one time. It worked out real well. Most generally I don't have a shot straight down. Really nice buck!!
I wouldn't, there are multiple times every year when a deer is standing/walking where it is the "only" shot. I don't take what I consider low percentage shots. I like high percentage shots as they usually end well. Being the only shot doesn't justify taking it . That's how I see it.