If i'm not mistaken, when I hear the term "modern" yang I generally liken it with the standardized forms that are used for competition. This includes the 24,48, and 42 movement hand form in addition to the 32 and 42 sword form.
I personally feel that taiji can be whatever the person wants it to be. If you want it to be for health then you will naturally pick out the health aspects of the teaching. Likewise can be said for the martial or spiritual side. I'm not a fan of having one or the other forced on me. I've been to more "martially" orientated schools and I felt that intention of the movements and such really "disharmonized" my mind, so to speak. Same thing goes for the strictly health aspect of teaching, if it's too caught up in the health side ( i usually liken this with new-agey kinda stuff) then some of the martial concepts that taiji was founded on is lost. Concentration is then focused on health and happiness but what about proper structural alignment and notions of qi and intention (yi). But sometimes if one has trained before then sometimes one can instill the martial side to a health-orientated training.
Kinda interesting how he said that they all come to the same result. Kinda similar to a quote a read in a book: There are many paths to the top of the mountain, but once at the top, we all see the same moon. -- Zen Mind, Beginner's Mind
I've heard notions that the traditional sets tend to help in martial training due to the repitions. Kinda like when a boxer want to work on his jab, he does a lot of jabs. I've seen the traditional set before and it does have a lot of repititions but this can either be seen as a positive or negative depending on your perspective.
As for being secretive on the martial side of taiji, I think it depends. My previous teacher, who i hold in high regard, new students came and asked about the fighting applications right away he would not talk about it. This type of questioning can give a lot of information on the inquiring student and the teacher can then answer accordingly. Can sometimes be seen as a way of filtering out. I was telling a current friend of mine how when I initially started training in wushu a long time ago, i really liked to fight. But after practicing wushu for sometime with my instructor I didn't want to fight anymore but strangely, now that I don't want to fight anymore, I feel that if I were to get into a fight that I could probably do a lot more damage now than before. My friend likened it to a "traditional" saying in that "when the student does not want to fight is he taught how to truly fight" or something along those lines.
good luck with your search.
A.