New stereo version? I haven't made a new stereo version.
The 'new' 5.1 mix is simply a better quality upmix of the same stereo track I'd used before. Improved channel separation and an edit to the level of one bass effect are the only things that were changed—the stereo source hasn't been altered in any way. If you have the TeamBlu SW77 that just came out, it can be found on audio track #2. But since not everyone seems to have it, I can upload it somewhere, sure.
While we're on the subject, I'd like to take a moment to reiterate something I've mentioned before, but bears repeating: if you're listening to my 70mm recreation on a stereo sound system, and not a 5.1 system, significantly better sound quality will be attained by choosing the stereo track instead of the surround. This is because there is a certain amount of crosstalk between the front and rear channels which even the best upmix can't fully separate, and with a delay being applied to the rears it is inevitable that there will be phase distortion when they are recombined in a downmix. The technical term for this distortion is 'comb filtering', and it manifests as a strange sort of warbling instability and hollowness in the sound due to the unpredictable ways in which certain frequencies cancel out and others become boosted. I did my best to minimize the effects of the comb filtering by manually editing the rear channels after upmixing was performed—by shifting the surround delay to 10 milliseconds rather than Prologic II's minimum of 15, and by inverting the polarity of the right surround, I was able to make it sound significantly less distorted when downmixed than it otherwise would have been. (The inversion of the right rear also had the effect of decorrelating the mono surround effects from each other rather than allowing them to phantom image behind the listener, giving them a more diffuse quality.) If I hadn't performed these two steps, downmixing the 5.1 track would sound far, far worse than it does now.
So while the downmix I've described does sound acceptable enough for me to not continually fuss over whether the stereo version is or is not included on any given project, it really is much better just to use the stereo track when listening on a 2-channel playback system. The sound is purer since there is no comb filtering whatsoever, and the lack of an LFE channel is a moot point since this is almost always dropped from downmixed 5.1 anyway.
If I could be absolutely sure that no one was ever going to downmix the upmix, I would have kept it closer to the Prologic II output and not bothered to try to make stereo playback of the 5.1 work. In such a case I would have insisted upon the stereo version also being included, preferably as the default track on a disc, with the user having to manually select the 5.1 if they had a surround system available. But since I don't have that level of control over how other people listen to it, some flexibility is in order.
A few months ago there was some discussion of the merits of DTS-HD MA vs Dolby TrueHD for authoring custom Blurays. Since I'm able to use the Dolby Media Encoder application, TrueHD would have been my first choice, since the format allows for any given surround mix to also include a separate stereo version within the same MLP audio stream, which the decoder would automatically select when the system was set to 2-channel playback. This would ensure that the proper mix was heard regardless of what kind of sound system was being used, without the end user having to select a separate audio track. But since TrueHD's implementation on the Bluray format requires that it also contain an interleaved AC3 track for backwards compatibility, and since only a few absurdly expensive authoring programs have the capability to interleave MLP and AC3 in the required fashion, it doesn't seem to be an option. Alas . . .
Anyway, I'll get to work on uploading the stereo 70 track soon.