Wat?
It's difficult to a) get any range on anyone with the biorifle, and b) actually dodge their fire. Short thin corridors that give you nowhere to go (and house the bulk of the health pickups), and thin enough to only just let you and a well aimed bio glob graze each other are not conducive to a healthy 1-on-1 DM.
It all turns into a game where both players uses only the Bio secondary, since you can glob anyone who appears from a corner or whatever without them being able to do a great deal about it. The only effective counter, is also using the Bio, or using rockets. In both cases, you still get globbed and killed. The other problem, is you can't hear people with a charged up Bio - but you can for the Impact Hammer, and to a lesser degree, people charging rockets.