If the only keybinding you change is medigel to facilitate reload canceling, you can substitute an arrow power for it with a GPS or Graal.
For me, with him, the key is playing on a big level where you can control the spawns. The arrows auto-home in even if you're not targeting the enemy as long as they're fairly close, so on a level like london or condor you can take out enemies from halfway across the map. Combine that with cryo ammo to keep them at that distance and against certain enemies, like geth, you can go an entire game without getting shot once. On the other hand, if you let them get close it can be an incredible pain. I had a game recently with this insanely annoying sexbot on giant; when she wasn't there, the enemies would spawn on the other side of the map, and all die coming down the ramp. Seriously, one at a time in a daisy chain, it was beautiful. And then she, the bosh'tet, would run into them, make phantoms spawn behind us, and get everyone killed.
*Deep breaths.*
The two enemies he has the most trouble with are phantoms and praetorians, as phantoms will dance around your arrows indefinitely while praetorians will just be straight up immune to 90% of your damage until they're close enough to land. The GPS deals with the phantoms(stagger, then follow up with arrows), but the only real solution to praetorians is to run up to them, get them to land, and then pound them to death. Fortunately you do a lot of damage.
Oh, and take a grenade capacity mod. I used to take melee bonus gear, but eventually I realized that it's better for your DPS to not have to run for grenades at a bad moment. Plus, it gives you the capability to spam mines in situations where you might otherwise use a missile anyway. It's just convenient.