When I was talking with someone who observed some fed testing involving the 155's in previous times, he said they found that over time the 155's were hard on guns.
In 2009 Winchester received a contract to supply the ICE division of the DHS with up to a maximum of 200 million, 135gr JHP 40 cal. rounds over the next five years. They were intended for the office of Field Operations of Customs and Border Protection. I haven't kept up on that contract. I have heard, however, that the 180gr .40 loads are regaining interest among other fed agencies.
http://www.winchester.com/library/news/Pages/Winchester-Awarded-Contract.aspx
I've never selected my ammunition based upon what various fed agencies may be using at any given time, though (as their reasons for their selections may not mirror my own).
I tried some different lighter weight .40's over the years, and although I was issued the 165gr RA40TA T-Series load for a while, I tend to prefer the 180gr loads from among the premium lines of the big name companies. I've carried some of the old-style JHP's, though, too. Just depended on whatever was being issued and/or whatever I had at hand for off-duty .40's.