One word to describe these new re-releases -- ABSOLUTELY FABULOUS!
(yes, I know that was two words)
There is no sense in discussing the performances, except to say that the M3 is as close as I get to an absolute top choice in any Mahler symphony, while both the M4 and M7 are easy top tier selections of mine.
So, is it worth paying full price + international shipping charges to get these from Japan -- Absolutely! These releases are an absolute revelation in terms of sound. The sound is sharp and three-dimensional, while individual instruments are distinct and well-articulated. There is very little, if any, congestion in the tutti's and very little stridency in the sound. The main thing that is missing is the real deep impactful bass (i.e. deep bass drums), but bass is much tighter than on the CD releases. These are 5 channel releases, but the rear channels are used only for a small amount of ambient sound, which probably adds just a little three-dimensionality.
I found it interesting that in the M4 finale, Reri Grist's voice sounds like it is anchored in the center channel, but every bit of it is coming from the front-left, front-right speakers. It is rather strange that the sounds cuts off quickly at the end of some of the movements (M3-1, M3-6, M7-5 are very noticeable). I also noticed a very minor sound problem at 4:49 of M4-3, where there is a digital-noise/electrical buzz sound (lasts less than a second).
I will be getting much enjoyment from these SACD's over the holidays.