I practice Chen Style, but it really isn't the main focus of my training so I am probably not the best to comment but I will give it a try.
While Chen is reputedly the original system of Tai Chi and was always a fighting art in the true form, I think that for most people its application is somewhat obscure. Some movements have clear and obvious application while others are less clear and more subtle. Much of the lack of understanding of the fighting side of Chen and any other style of tai chi comes from reality of the modern world, a broad proliferation of the art where it is no longer studied as deeply as it once was to gain a real understanding of its useage. Most people who practice it don't really need to use the art as a fighting art, so its fighting capabilities are becoming stagnant in most cases. Nevertheless, it has strong fighting applications for those who understand it on that level. I think that not many people really have this understanding anymore, even among those who claim that they do.
There are stories around the great Chen masters of today who can still use the art effectively. According to my sifu, his sifu Feng, Zhi Qiang of Beijing still accepted all challenge fights until he was well into his 70s and remained unbeaten, for example.
One thing that I have noticed is that most, if not all, of the Tai Chi masters who can really fight also have extensive backgrounds in other Chinese martial arts such as Shaolin and Choy Li Fut. As they grew older they shifted more and more to Tai Chi and did less and less of the external arts. I sometimes wonder, however, if the experience with the external arts is what gives these people an edge in being able to utilize their Tai Chi effectively in a fight. I believe that the external and the internal arts each benefit the other. One alone is effective, but when practiced side by side they each make the other stronger.
While my primary focus in training centers around Tibetan White Crane and some Shaolin based material, I do include Chen within my practice. I definitely see my Crane as a more easily useful system than Chen, but I also feel that Chen has given me some extra "bonus" that Crane alone might not have given me. Exactly what this is I cannot really describe clearly. Rather it is something nebulous that I feel is simply "there" and perhaps helps my Crane. Maybe it is nothing more than a greater understanding of being relaxed, which is necessary for most Chinese martial arts to be effective.
I know this post is not very clear and concrete, but hopefully this will give you something to consider.
