Here is a bit of Metassino's break down of the score that you got if you bought the original SE with the booklets.
Here's him speaking about the ORIGINAL cue:
" The "Main Title" leads into The Ice Planet Hoth, the beginning of which was eventually rescored with "The Imperial Probe" (see track 4). Both versions start with dancing flutes and a rising horn phrase over which Darth Vader's theme is introduced by a solo piccolo. This original version continues with the entrance of trumpets, leading the orchestra to a great crescendo of Vader's theme and beginning an extended sequence of more than sixteen minutes of continuous music. Nine minutes of this music was either dropped, rescored, or replaced by other cues. A grandiose passage leads to a rhythmic section featuring the tuba, followed by a sudden quietness as Luke's tauntaun is seen striding across the glacier. Strains of the main Star Wars theme are played by a solo trumpet as Luke appears, and then, as he converses via comlink with Han Solo, the French horns introduce the new theme for Han and his growing relationship with Princess Leia. Bombastic percussion and trumpets intervene when Luke is suddenly attacked by a wampa ice creature. This is followed by unused militaristic music for Han Solo's arrival at the Rebel base."
Here is him talking about the alternate which is used in the film.
"Following Luke's recovery, the focus returns to The Imperial Probe, beginning here with the subtle, atmospheric piece which in the finished film replaced the first portion of "The Ice Planet Hoth." Vader's theme is again played by solo piccolo, and then suggested subtly by the quiet chord progressions heard during the probot's landing."
I honestly do NOT believe the sequence was changed at all EXCEPTING in the music. Metassino would have mentioned it. If you read his work for, say, return of the Jedi, when he talks about the opening cue, he explains how the final portion was for a never before seen edit of the film.
I don't want to be rude, but that really how it was intended... AND how it was suppose to be synced. In the film it's a few seconds off from that syncing... which would be my only advice to Ady if you choose to use the version in the film, see about resyncing it.
I'll post an example.
As for the original being too loud... You have to jump back to the year this came out... people had just finished the phenomominon that was Star Wars... now they're going to see the new one... and THIS is how it begins... Not with the good guys... not with seeing the falcon or Han solo... or Even a planet really... It begins with a star destroyer shooting little things out which until it crashes and opens, you don't realize is a probe droid.
I think the music could go either way. Personally, I never really like how the quieter music fit... but if williams had made a third alternate of quiet music that fit as well as the loud original version, I'd say to use that...
EDIT: to then comment on your edit Ady, it's kinda cool... but I think it speeds things up a ALOT...
The thing you all aren't getting is that the music you say should cover Luke on the taun taun from the distance is a DIRECT QUOTE of the music from the Probe Droid Destruction sequence!!... lol... so it's...quite evident it was meant to cover the Probe Droids reveal...
Which in a way kinda works how you have Ady... it kinda hints to what it was and tells you (musically) what it is... but visually it hides it...
The only issue I think is that for people to get it, they'd have to have heard the "Probe Droid Reconnassiance" cue...and if they havn't, they might not understand it to mean such...