Inconsequential?
Here's a team friendly i played during the summer:
http://www.youtube.com/watch?v=Fch66F9uufs
going by the time on the in-game timer,
7:10 Wind formation starts
6:58 This is when i start traveling upwards. My second jump is also wasted.
6:38 The stage returns to Normal. At this point I am airdodging so Pit's arrows don't kill me. If it was a character that couldn't reach me with something, DB1 can still be used to stall for longer.
6:30 I'm visible on screen
Let's assume that there's some point above the blast zone where I can not go any higher. Some sort of limit. So it will always take 8 seconds to be visible on screen again. If i had started at 7:10, i would still be up there for 40 seconds, until 6:30. Assuming i use DB1 to stall for longer, let's give it an extra 5 seconds. And then not wasting my 2nd jump, an extra second. That's 46 seconds of being 100% safe and assuming there is no limit above the blast zone, i can stay up there for longer, since i lost 12 seconds of rising, plsu the amount of time it would take to fall that extra distance. If a match is something where my opponent is above 150% with 45 seconds to go, or i have a 50% lead, i've already won the match. Snake can cut a 50% lead down to nothing in less than 10 seconds on any of those 3 stages you listed, or any other legal stage for that matter. That should never happen.
You asked how long they could stay up there in your thread, here's your answer for marth.
Don't say it's inconsequential though.