There seems to be one thing people missunderstand time and time again and record companies cash in on this.
remastered means the origional 2 track (in this case)mixdown from the multitrack recordings is sent to a mastering house or person who should have a well reated accustic room with as accurate monitors as possable. the (re)mastering process usually involves proccessing the recording to make the best overall sound on as many systems as possable in as many rooms as possable, this is usually done by careful multiband compression, selective equalisation of frequencys and often limiting to trim the peaks to a more manageable dynamic range (ie so you can hear the quiet parts easily and the loud parts in relation to each other, it also helps make it radio friendly if say singles are intended) then the tracks are made to comply with the red (or orange) book standard for say cd with spaces between tracks and lead in and lead out passages. the material is then compiled ready for approval and sending to the pressing plant. this process can nowadays bring out un noticed or unheard parts of the mix and increase clarity, it doesnt in any way mean the track has been remixed.
the 5.1 version will have requiterd the orogional multitrack tapes to be probably remixed taking into account the 5.1 placing of the instruments in the mix and and i would expect taking the opportunity to make the recording much better using modern effects and processers. this then when finished will be sent for mastering.
i would have thought that they would have also remixed the tracks for stereo again taking advantage of the new options ab the hindsight of band and fans optinions over the last few years. i think still life could sound really great, although it was ok in its first version and also ther glitches can be corrected.
perhapse the rest of the albums could be remixed at some point as i think all the albums up to bwp could do with a little bit of attention.
remastering is a quick money making fix thats all