I don't think this will go out of style, especially given the button stance.
I wouldn't call the 150 fabric flimsy (which at least to me sounds like implying poor construction).
It's true a 150 will be somewhat delicate, but I think this is far more of an issue for suits, where the seat and knees will sure wear sooner than you'd like or expect.
I have a 150 RLPL blazer that I like a lot. It's truly four season and very versatile.