I am never a fan of that hidden track nonsense, which is tacked on to the end of Stranger in Your Soul (that I deleted from my version of it a long time ago), but otherwise Bridge Across Forever is a perfect album, as is SMPTe.
A very long time ago, I took the end-jam of SCP from the end of SIYS and re-inserted it at the end of the track proper (undoing the fade-out and fade-in as well). Getting them to line-up perfectly took a bit of work, but now the song is an epic 17:06 long, and the sound effects at the end of it blend perfectly into the intro of the title track. To me, it's the complete way to listen to the album and I haven't heard it any other way in well over a decade.
Anyway, if we can assume for the sake of argument that the forthcoming 5th album is around 70-75 minutes and that all or most of it played on the subsequent tour (whenever that is), it will be interesting to see what songs from the first four albums make up the rest of the set list. I fear that all of the 20 minute plus epics will all be lumped into several medleys, that way they can play some of all of them, and I would imagine a chunk of The Whirlwind would get played again. Would be cool to see the return of Mystery Train.
I've thought about this as well, and I'm sure they'll play the whole new album (because why not?). I'd REALLY love to see them bust out one of the Whirlwind bonus tracks (particularly Spinning), and like you, bring back Mystery Train as well. I'm sure there will be the typical Whirlwind Medley during the main set, but I can see them doing a new encore medley, which I would like to see them do a condensed version of the BAF album, since there are repeated themes and motifs between all 3 of the longer songs, they could easily mash them all up and make a solid 25-30 minute medley of the three songs (DWTD, SCP, and SIYS). So 75 minutes of new material, 60 minutes of medleys, and another 15-25 minutes of other material from SMPTe, The Whirlwind bonus disc, and Kaleidoscope (Shine and Black As The Sky). I don't see them bringing out any part of Into The Blue or Kaleidoscope (the song), unless it was another condensed medley of the two of them, but even without that, this is already reaching 160 minutes, and that's a lot of material for a tour already, but they have played 3 hour shows before, so who knows.
On the topic of weighing Whirlwind against SMPTe and BAF, for me, I discovered Transatlantic in 2005/2006, and fell hard in love with their first two albums, and so my wait for a third one wasn't as long as any fan who had known them from the start (almost half as long of a wait, really). When news broke of the third albums' sessions beginning, I was ecstatic, and I think my excitement carried through that long wait because when it came out, I could not stop listening to it. For about a year from its release, it was played in heavy rotation, despite all the other great new music I picked up in 2009/2010. To this day, I still really enjoy it, but still not as much as BAF, but as a whole, The Whirlwind is probably one of my favorite albums of all time, and a very close second to BAF.
As for Kaleidoscope, while I don't love it as much as the other three, it's still a great album, and I often myself going to it when I feel like listening to TA. Maybe because it's their latest album, or perhaps I kind of burned myself out on TW for the better parts of the 2010s? Who knows, but I still really enjoy listening to it.
I've been spinning TA music a LOT in the last month or so, and even re-watched all of the making-of documentaries, and the concert videos, tour documentaries, and every other piece of video by the band, and it always reminds me why I love them and their music so much. To me, they're like the Avengers of prog rock. Individually, they've had some great music with their respective bands and solo projects, but when they come together, it's an EVENT, a spectacle that can't be missed, and they bring some of their best music and playing. If I had just known Pete Trewavas as the bassist for Marillion, he probably would not have stood out to me, but as the bassist in Transatlantic, his playing is some of the best I've heard in the genre (especially on The Whirlwind, which, thankfully, pumped up the bass). And compared to their best work in SB and TFK, Neal and Roine's stuff in The Whirlwind is on par with all of that IMO. And of course, there's Mike, but as a drummer (who really enjoys most of his work), I can't help but be impressed by the stuff he does in TA.
I'm very hopeful about how well TA5 will turn out. It's their second longest gap between albums, and both Neal and Roine have been fairly prolific in recent years (as has Pete as well, with Edison's Children and reuniting Kino), so I hope they saved some of their proggier material for Transatlantic! I'm hoping Neal's July IC Newsletter gives an update about the album!
-Marc.