The Unreal version's projectile-based fire is incredibly quicker, yet easier to use in my opinion...
"And" I believe is the conjunction you were looking for
Juggling with the UT3 stinger is a bit tough, because you really have to anticipate the hit. I usually scatter a "every other shot" type pattern, where I put one where they'd go if the last one hit, and the next where I think they'd go if it didn't. I also usually switch to the other fire after I get a couple in them to finish them off.
It's really weird to find the sweet ranges for the two different fires. The projectile fire is extremely accurate, so you'd think it'd be better at range, but the time to target hurts a bit, and the cone and rate of fire on the scan fire makes it feel much more devastating up close, but because it's instantaneous you wanna use it at the longer ranges...
I think that's the problem. It's hard to really get a good feel for the projectiles, because it's a constant debate as to which one is more effective at what ranges. I tend to think they are equally effective at each range, and it really depends on how much damage you gotta do, and or what weapon you are facing. VS rockets or flak, I'd say goto to projectiles to create space between you and your target. VS link, sniper, or shock, the primary is the way to go. Primary VS weaker targets as well, secondary if they are belted, and you don't feel like trying to steal it.