Here's my take on it-

The VSP is an all around "better" bike. Add up all the improvements and it's just a really nice package of the "best" frame and the "best" parts of the time. Any of the "upgrades" make a really nice bike that much better.

I think, barring any significant weight differential, the big difference in the SL/SP mix and Tenax will probably be the difference in your head to you. Although it seems silly- that's a really important part of what your bike is to you and your confidence and trust in what your bike can do- not JUST a matter of your prestige in having an awesome bike.

I currently have an 84 VSP and had an 86 Voyageur. The 86 Green is what I think of when I think of "Schwinn Voyageur." Unfortunately, I didn't get a good opportunity to compare the VSP to the Voyageur, or even to really evaluate the Voyageur. I got the Vgr as a frame/fork/extras- I built it up with the stuff I wanted on it- but around the time I was kind of finalizing stuff with it, the VSP dropped into my lap. I had some unique tires on the wheels I acquired for the Vgr (Specialized Expedition 27x 1 3/8" on Avocet hubs on Super Champion rims)- the only problem is they were really old an I didn't trust them- so I never REALLY rode the Vgr.

The VSP is an EXCEPTIONAL bike. Everything on this bike is the very best in touring bike components of it's day. I've swapped out a few things, but kept it a Shimano-free build like it originally was.

I have a 1985 Trek 620 and a 1985 Trek 720. They're both very similar. The 720 is 531C and the 620 is 531CS. 531C is 531 in the frame, stays and fork; 531CS is 531 in the main tubes, but Reynolds CrMo in the stays and fork. I have them built up pretty similarly and I don't detect any weight differential between the bikes- either in picking them up or in riding them. In terms of the ride- I've found the wheels make the biggest difference. I've got Phil/Super Champion wheels on the 720 and Avocet/Super Champion on the 620. As amazingly smooth as the Avocet hubs are, the Phil hubs are smoother- and that does show up in the ride- even comparing different wheels on the same frame.

When I ride the 620 I think "this is my favorite bike." When I ride the 720 I think "this is my favorite bike." When I ride the VSP I think "this is my favorite bike." The concept of better among the best is beyond my ability to tell. However, the 720 is more rare and I'm aware it has more cachet and prestige surrounding it. Of course that enters my mind while I'm riding it. But it also enters my mind about how incredible the 620 is and how seriously awesome and underrated the VSP is when I'm riding them.

As I recall, the Passage had a longer wheelbase, Tenax main tubes with CrMo stays but a Hi-Ten fork- that's why I suggested replacing the fork- otherwise that seems like a REALLY good and well thought out bike. If you're moving the Passage along, steal those Sachs/Huret shifters- Seriously, among the very best.

I guess what I'd do is make a frankenstein and take the nicer frame (or the frame you like the best) and the best bits of what you've got on the Voyageurs and the Passage. I'd keep the MT 60 derailleurs. If you're into indexed shifting- keep the 87 shifters. If you're into friction shifting- the Passage's Sachs/Huret shifters are among the very best ever, and there's a lot of people who love the Shimano spring/ratchet shifters on the 86 Voyageur. I trust the Sanshin hubs more than I trust Maillard- but I'd take the smoother of the two.