Having just finished my 61st year of bow hunting (I still use a vertical recurve in addition to my Excaliburs), have some thoughts to share.
Except for the very small percentage, deer hunting @ 100 yds is not advisable. I don’t consider myself normally in that percentage.
Here are some beliefs I hold.
1) Deer movement can be fairly predictable. A relaxed deer lowering its head to feed with its head turned away from a shooter will virtually never move its body during the arrow flight, regardless of how long that flight might be (<1 sec). I think a student of deer movement can pretty well overcome this obstacle.
2) Ducking the arrow or string jumping is a non-factor for shots >30-40 yards, IMO. At 60 yards, they’ll just stand and look in that direction if they do anything at all.
3) Arrow noise. Arrows can be very quiet and can be very noisy. I make mine very quiet. Helical, large profile feathers or light (thin) vanes and large vented broadheads can sound like a freight train. Stiff, low profile, offset vanes and certain low profile fixed or certain expandible broadheads can be virtually silent.
4) Xbow noise. At 40+ yards, tends to freeze the deer in place. At 60+ yards, virtually a non-factor.
5) High winds. Not good at 50-60 yds+ but can be well managed with practice out to there and beyond. Definitely range limiting.
6) Low wind. Not as much effect as many think. Hours of practice, intentionally shooting in the wind helps.
7) Shooting rests. I do all my arrow work ups and sighting off a benchrest set up. Then in my blinds, shoot off a monopod, and out of my tree stands, a gun rest. It’s a must to practice this way. These two rests are not benchrest set ups. They need practice to see how well you can really shoot off them.

9) Range estimation again. Unless you’re hunting over bait that you have meticulously measured, long range xbow hunting just is risky at best. Trajectory and range estimation will cause major problems. There’s just no leeway for error. This is the problem as I see it. My xbows ( 2 M405s, BD400, M380) are incredibly accurate but much slower than the 425+’/sec xbows. They have an advantage! They do increase the “max ethical range”.
10) I do long range, xbow hunt varmints. I hate bobcats and coyotes!! They are smaller, and more prone to try to move out of an arrow’s way. Hunting them at longer ranges can greatly hone our deer hunting skills.
11) I have to consciously resist aiming at the center chest of a deer. It’s just hard for me to aim at the lower 1/4th like I should. I’ve noticed that as the range to the game increases whatever it is, aiming for the center becomes harder for me not to do. Maybe others experience this too.
12) FORGET any concerns about lessened energy at range. Arrows slow much less than many realize. Energy reduction at distant ranges is not very much less than at release. I consider energy loss with range, a non-factor.
13) When all of these factors are put together, it is reasonable to conclude, IMO, that virtually anyone’s maximum ethical range will be well below 100 yards, except for the very rare exception. Practice on those stinking coyotes!
14) My background is of a very analytical nature. Prejudices such as , I’ve always believed, I’ve always heard, common sense dictates, etc have no place in establishing facts and givens. Empirical approaches are far more meaningful. This is what I’ve tried to do.
15) Give additional factors you think both pro and con.