Also, I read another link about how a 1D kalman filter basically converges its kalman gain into a steady state gain, basically becoming a low pass filter.
In light of these "discoveries", I'm going to just play around with the 1d kalman filter abit, see if I can get a bit more out of it. For the breath controller project, I will look into using an analog low pass filter as a antialiasing filter for the ADC. I believe using the analog filter will remove any unwanted frequencies above the nyquist rate I'm sampling at (I'm thinking at least 4x oversampling), and then use a digital low pass filter internally to smooth things out.
Other news, London's weather is really nice now, but it was really very hot over the weekend, a sudden change. Not taking it well, I'm kinda having a feverish spell the last few days, it's one of those feeling ill but not ill enough to take a sick day things. Gah.