I'm probably answering too late to not get lost at this point in the sea of people answering regarding products not being ruined, but as far as actual company culture, E Systems survived quite well and intact after being acquired by Raytheon in the late 90s. One of my earlier jobs in Richardson, TX was at a facility that originally belonged to E Systems and I worked on one of the longstanding programs they'd had for decades. It very much stood out as being nothing at all like the rest of Raytheon. They had exemptions for nearly every corporate policy. People on any other program got moved around at will to meet the needs of the larger company, but anybody who had been with E Systems stayed exactly where they wanted to be doing what they wanted to do, even decades after the acquisition. They kept all of their original scheduling policies, continued using the same project management methods and tech stack without having to give in to corporate flavor of the month "Agile DevOps transformation" stuff that everyone else had to do.

It's honestly probably still the best job in software I've ever had, and the actual system I worked on is still the most impressive I've been a part of, the exception to the rule of government shit projects, heavily classified but absolutely miles ahead of the closest commercial analog. If the pay wasn't so low, I'd gladly still be there. It's a dream job in every way except compensation.