I'm a pure syringe gun user, myself. It's excellent at countering flames, as people have already said, and as khaotic calculated out, You heal back to a safe range 150% faster. That's ridiculous.
In any scenario where your buddy dies, you should be running away, not charging into battle. As Pepper said, the terrain is your best bet. The medic is hardly built for direct combat (much to the chagrin of many a battle medic), and while yes, the DPS can be impressive, you're better off over all when you don't need health all the time.
The key to being a good medic is overall longevity. When I medic (and when others medic me) it happens very often that just as you see your buddy taking damage well past what you can heal, you back off to max range, just in case. When he dies, you bail, and you're back home with most of a charge. If you're not actively trying to shoot at people as you run, not only do you run faster (going forwards instead of backpedaling) but you do a better job of hiding.
What's more obvious, a medic dodging in and around scenery trying to get away, or a medic who's actively trying to maintain line of sight so that he can shoot you?
And one last question to those of you who support the blutsager: How often do you actually use it's healing effects? I rarely use the syringe gun anyhow, because, as Quaffer said, your best weapon is the guy you're healing. So, I'd rather have a passive bonus than an seldom-used active one.