I've tried both the Lazer and the Zena and prefer the Zena. The biggest reason for me is that the Lazer has a cumberbun, whereas the Zena is basically a corset with a wing attached. I prefer a minimalist style with no need for pockets, thus the Zena is perfect since I can add on a pocket when I need one. As far as the Lazer being a "travel cut" of the Stiletto, it would probably be more accurate to say it's a LADIES cut instead I'd think.
I've been diving my Zena for almost 6 years and have going on 400 dives with it. Not only does it look as good as it did the day I took it out of the box, but of those nearly 400 dives, about 150 of them are shore diving on Bonaire. NEVER have I thought my Zena was hard on my lower back, but I also was one of the voices that urged ScottZeagle to develop a lumbar pad for the Zena since it's nice to have that space filled in for comfort.
I will say that how the Zena is fitted on the diver's body is exceedingly important for comfort. If it isn't properly adjusted at the start of the dive, I can only imagine how uncomfortable it could be. When properly adjusted, the Zena should literally never move on your body. You should never feel it shift or have any tank roll, period. With 6 points of adjustment and 3 different pieces (shoulder, front panel, vest) that you can mix and match for size, the Zena becomes as close to a custom fit BC as you can get (as do ALL Zeagle BCs). As for travel, my Zena has the 24# wing, weighs about 5 pounds, and folds up quite small with the only limiting factor being the inflator hose.
Clearly I'm probably the Zeagle Zena's biggest fan, however, I will say it isn't a BC for everyone (like no single BC is right for everyone). It also isn't a BC built for cold water (dry suit) diving. If you need a cold water BC, stick with the Lazer or the Women's Ranger.
Bottom line is really to find what fits you best and you like the most. You might check prices at ScubaToys and find yourself pleasantly surprised that you can afford more than you thought. If you call them with your measurements, they'll also put the right components together to build a custom fit BC for you. They'll also do that for both the Lazer and the Zena for you, shipping both to you to try and have you send back the one you don't want.