I love OcenAudio, it's SoundForge for the new millennium =)
It is, however, not the same type of app. OcenAudio is a wave editor, so only one file at a time. Audacity is multitrack, and has a project structure much like a DAW without the MIDI stuff.
Speaking as a producer who's programmed a lot of natural-sounding drum tracks...
There are plenty of variables other than velocity -- location on the drum head being the prime one, but there are others. Because of this, sampling an acoustic drum kit involves capturing a suitable number of random variations, and the end result is often gigabytes (i.e. hours of content) in size, even though each sampled hit is just a few seconds long. Not having enough variation in your sample set makes the programmed drums sounds unnatural, since excessive repetition doesn't gel with how we experience acoustic drums.
Certain variables are more important than others, though. One notable sound is the 'rim shot' which means striking the drum head and rim simultaneously, which causes all kinds of constructive interference and results in a very powerful sound. It's the holy grail of rock drumming. In drum programming, rim shots are often a separate stack of samples with its own velocity layers, each layer with a set of random variations.
It is, however, not the same type of app. OcenAudio is a wave editor, so only one file at a time. Audacity is multitrack, and has a project structure much like a DAW without the MIDI stuff.