Fascinating to compare these!
IMO, Sam's use of reverb has resulted in a more '3D' mix with greater depth and space for all the different elements.
At 1:26, Rich's new brass-like melody arrives without fanfare, whereas in Sam's mix it is 'featured', resulting in more variety during the track, and because of the greater 3D-ness your ears can continue to follow the piano or focus on the brass, or flit to the percussion... It just sounds more 'varied'.
Although the notes are all the same in both mixes, I hear so much more movement in Sam's mix.
At 3:01 when the bassline comes in I prefer Rich's mix because the bass sound has a richness/warmth that's lacking in Sam's, but this is the only time Sam's 'thinning out' didn't work for me.
At 3:56 when the choir comes in I once again like the warmth of Rich's sound, but Sam has once again pushed the choir further back so you can hear it as yet another separate element for more overall mix depth, so Sam's wins for me here, especially when at 4:06 the 'hammer horror' strings come in from a more ghostly and distant background.
Once again at 5:07 when the jazz piano solo kicks in it sounds great in Rich's original mix, but by placing it further back with more reverb, Sam's mix sounds 'bigger', and to me gives a greater impression of a group of musicians playing together in an acoustic space, rather than a group of instruments being played by one person and panned across the stereo image.
Overall, I love what Sam has added to the mix , and it's certainly taught me some stuff about using depth as well as width.
Bravo Sam, but of course bravo Rich for the track