I've been studying and comparing results of the two surgeons for awhile now, including reading every post on this forum about either of them, seeing what ->-bleeped-<- has to say (Haben did a great AMA there awhile back), and just trying to be as objective as possible. It's been hours upon hours of research.
I definitely get the impression Dr. Haben's technique is evolving over time. In a post from a couple years ago when someone asked him how many of these he's done, he said 200+ VFS procedures - when Dr. Kim was starting to become known for this in 2011, he'd only done ~150. Keep in mind, both surgeons are about the same age, each with <15 years VFS experience. Yes Dr. Kim has been doing VFS longer, but we're getting close to Dr. Haben having as much iteration as Dr. Kim had when his work started taking this forum by storm 3-4 years ago.
The matter of microscalpel vs laser seems debatable. It really comes down to the amount of precision used with the laser and whether it's excising the exact same tissue layers as a microscalpel. If it does, I'd imagine laser to be slightly superior, since the cautery action would yield less blood loss. Most likely Dr. Haben uses laser because his initial "claim to fame" was treating laryngeal cancer patients using lasers. (If you've ever heard someone who had to use a robo-talker, or like Dr. Leis who had radiation treatment, you can appreciate the value of Dr. Haben's innovation.)
As far as suture technique, compare the example on his website
http://professionalvoice.org/images/FIGURE%201-500.jpg to the technique used on a recent poster
https://www.dropbox.com/sh/js9jtumq725it8b/AAABgeHOkLqXe8Jb_l2RpLLla?dl=0&preview=Before+and+After.jpg who ended up very happy with her outcome. Obviously each person's vocal folds would be a little different, but just looking at the photos, I notice a number of big differences. The newer suture material appears thinner, like it's more suited for precision work. Also, the placement of the sutures appears different - he places the long cross-suture high now, rather than across the other two. The two sutures near the 'new' commissure appear about as deep as the earlier example, but they have a new angle and placement, rather than just parallel horizontals.
Could Dr. Haben be adapting his suture technique? He did say in his ->-bleeped-<- AMA that he looks at every patient as an impetus to improve and is constantly evolving his technique. I cannot say without actually seeing immediately-post-op photos of Dr. Kim's suture work, but the "taper" principle could be working its way into the states. At the least, it looks like a night and day difference!
For my part, I'm likely booking with Dr. Haben soon. I think if you're within a day's drive from him, it's worth considering more than just raw experience - factors that could affect your healing and final outcome, like catching a cold on the plane, general travel fatigue, stress (or even risk) over N.Korea's recent saber-rattling, or just whether or not you have to go by yourself. (Two weeks overseas alone for surgery? Been there done that.) Besides, as word spreads that good VFS exists, we'll need more than one great doctor in South Korea doing it.
(I haven't really seen enough from Dr. Spiegel to feel confident in his VFS, or even that he's been doing it as long as he claims - small sample size includes one failed-but-not-botched result and one of questionable comparison - let alone to trust my voice to a general aesthetic surgeon rather than a voice specialist with proprietary surgical techniques.)