Everytime I say buy the 155 I hear mental thoughts of why would I. MBX needs a rental program, haha. 7 day rental, to try it out and see if it's worth converting.
I could see if you don't have any mags then buying 155s and 170 could make sense. But when you shoot other divisions just as often then keeping with the 140s makes it easiest.
I dont know, I just don't know.