I think you are going to have to go to MutiChannel drums eventually.
8ch drums wma is no bigger file size than the 2ch (see below).
and wav (or Flac)
Multitrack 8ch Drums 138.wavpak Multitrack 8ch Drums 138.wav You could have a Mixer panel as in RB, that pops up when new MultiChannel Drums are available:
>>> How many RealDrums were recorded using a midi Kit ???
None of our RealDrums have been recorded using a MIDI kit. They are all stereo recordings of a real Drummer in a studio. It would be the same as if you bought drum loops.
Though we use several mics to record them, all that is released is the stereo mix, and there isn't a way to isolate each instrument in the drum kit.
I think any new Drums you create should be recorded direct to multitracks with more mics then just several and have some midi drum/cymbal sensors also to get a midi drum track so you have an option to use your own Drum VSTi as well as have RealDrumCharts.
These are MultiTrack Drums I purchased, as you can see they come with MutiTrack Drum Loops also. I should also be able to use these MultiTrack Loops in BB with the MultiTrack Mixer for that Loop track.
This is wma though you could use another multichannel compressed format and use the same format in Mac & Win.
8 channel wmaFormat : Windows Media
File size : 1.65 MiB
Duration : 1mn 25s
Overall bit rate mode : Constant
Overall bit rate : 161 Kbps
Maximum Overall bit rate : 161 Kbps
Encoded date : UTC 2014-01-02 22:37:20.607
Audio
ID : 1
Format : WMA
Format profile : Pro
Codec ID : 162
Codec ID/Info : Windows Media Audio
Description of the codec : Windows Media Audio 10 Professional - 160 kbps, 48 kHz, 7.1 channel 16 bit 1-pass CBR
Duration : 1mn 25s
Bit rate mode : Constant
Bit rate : 160 Kbps
Channel(s) : 8 channels
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Stream size : 1.63 MiB (99%)
Language : English
2 channel stereo wmaFormat : Windows Media
File size : 1.65 MiB
Duration : 1mn 25s
Overall bit rate mode : Constant
Overall bit rate : 161 Kbps
Maximum Overall bit rate : 161 Kbps
Genre : Blues
Encoded date : UTC 2014-06-23 05:20:18.798
Audio
ID : 1
Format : WMA
Format profile : Pro
Codec ID : 162
Codec ID/Info : Windows Media Audio
Description of the codec : Windows Media Audio 10 Professional - 160 kbps, 48 kHz, 2 channel 16 bit 1-pass CBR
Duration : 1mn 25s
Bit rate mode : Constant
Bit rate : 160 Kbps
Channel(s) : 2 channels
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Stream size : 1.63 MiB (99%)
Language : English