Deadeye is very good at many situations at endgame. But to make the most out of her, you need to have a good sense of positioning and timings of the abilities.Her Tier 4 Upgrade that makes the E pierce through every minion is insanely strong if you redirect most of the minions to a choking point and can target the whole wave in a straight line, it can totally clear it by itself.Razorweed on T2 and Hard Knocks on T3 are my usual build, making her a very strong medium range with lots of AoE damage. Keep in mind you can jump and/or aim up to use the right click and make it go past the first minion in front of you hitting many behind, that "trick" can make a big difference of efficiency if playing solo or just when having minions right in front of you.
Sounds like you value damage over crowd control. Deadeye does decent damage. Her bolts fly a bit slow, so hitting at range isn't as easy as, say Gabby.