I've been using a Waverider for bio-feedback meditation for over a year now and I am very happy with it. It doesn't come configured for biofeedback out of the box - its original intention seems to be as a MIDI controller for converting bio-signals into electronic music.But WaveRider has powerful user-definable output capabilities: a large number of simultaneous MIDI output windows can be opened, each focussing on a particular part of the spectrum, or on hemispheric coherence, or on average EEG frequency, or on the ratio between power in two bands, etc. and each MIDI output can be set up to control a different parameter on the sound card synthesizer - e.g. note pitch, pan, volume, tuning, effects, or for that matter any MIDI-controllable parameter on your sound card.
Re your question about whether it could be set up to reinforce increased beta and decreased theta, or SMR / SMR+theta, the short answer is yes.
You could define a MIDI output for each of these bands using the "power in band" mode - i.e. you specify the frequencies at each end of the band(s) in question, and then the MIDI outputs will vary in proportion (or at your choice, in *inverse* proportion) to the EEG power in those bands.
What you get the MIDI to do from there is, if you'll excuse the cliche, limited only by the imagination in terms of the kinds of audio feedback signals that could be generated. I have previously posted a technique for producing binaural beats from such MIDI signals, tracking (or rather leading) the average EEG frequency lower for meditation purposes. This could equally be used to lead EEG into higher frequencies.
If you make your own *.sbk's (soundfonts for wavetable-type sound cards) you could trigger short *.wav files under certain threshold conditions to say something warm and fuzzy to encourage the patient, or start/modulate any other sound you have imported as a sample into the synth. By defining input and output amplitude ranges you can establish thresholds at which the desired combination of theta/beta is reached and the sound starts or changes.
You could, for example, use the MIDI to vary the beat frequencies in a layer-cake of binaural beat tones to lead the EEG in the desired direction, then trigger another sound to give reinforcement when the desired outcome is achieved.
WaveRider's features are too numerous to be described in a few words - it's best to test drive a demo version of the software. According to Mind Gear's catalogue re WaveRider at:
http://mind-gear.com/cat/waveride.htm
you can request the demo software by email to psafier@rt66.com .
You can also download or read about the binaural beat technique from that web page.
I believe that WaveRider/WaveWare also comes in a Mac version.