It needs a rework just as special ammo does.

Sniper rifles, long lanes and cover usually work

Bringing perspective from MnKB/PC side. Long-range fusions aren't really a problem over here. I can consistently dodge fusion / LFR shot with juking the shots next to cover. Stand right next to/out of cover on purpose. They see you and start charging the shot. Just before the shot fires flick to the side quickly and take a couple sprint steps so you move back behind cover. When you time that correctly they're already at the part of the charge when the shot is practically firing and they can't cancel it. They end up whiffing the shot to where you were standing just as you move to cover. I've had occasions where I've made a guy whiff 2-3 shots back-to-back like that. Juke a shot, then re-peek out of cover and juke the next. The timing's relatively easy when you get it down from the charge sound. Then mix in 1-2 handcannon shots or something per peek and you're outplaying them. Backup plan makes the timing a bit different but it's still doable. You just need to look at their actual gun swap animation instead of the longer charge sound and time taking cover to just as the charge sound starts. That's all from MnKB perspective. With controller sticks the quick flick is basically impossible to do. Can see fusions being more obnoxious on controller platforms for sure. Hunter dodge is probably the only chance controller has to replicate the movement. Also Backup plan is still broken on fusions in my opinion. You can counterplay it with cover, but it's an originally unique exotic perk that negates almost all negatives fusion rifles have by-design. It should be removed and replaced with quickdraw on guns that have it rolled already or something. The thing with fusions is that if you're caught in the open by one you're pretty much gone. Cover is the best counter. Or a snapshot sniper headshot before they finish charging/swapping.