I wish I could tell you, but I haven't ever used the 15x Swaros. I can't imagine the FOV would be much different given the specs. Definitely not a tunnel. The Swaros will certainly be in a class of their own judging from the dozens of other Swaro products I've used. If you can afford the Swaros, don't hesitate. If you can't, I think you'll be pretty satisfied with these. I just used them this morning between posts and spotted some elk while I was hand holding them. They were not focused right so not a great view. I got them on the tripod, took a few seconds to get the focus right (each diopter focuses separately) then got back on the elk. Very clear and sharply focused. Elk were at 600 yards and I was counting points on the good bull (bull was in the cows already!) easily.
I haven't had any hour-long sessions with them yet, but in the 20-30 minute range, no eyestrain for me.
All in all, they are a good tripod binocular for the money. I'll be using scouting all this month and on a September bowhunt if you can wait. I'll be posting more on the blog about them. Of course you could win them, too.