I don't know if it's better. I'm sure it has its pros. Like you said, having better understanding of their work problems. However, one thing that attracts some people to others is the fact that they're not just like themselves. Having differences can lead to learning new things and expand your horizons. It can challenge you and help you grow into a better person than you were without that experience.
I know couples who are both military but they work different fields. The fact that they're both military gives them some understanding and the lingo. When I'm hanging out with those groups all they want to talk about is work or things that they have in common with each other. I don't get much chance to talk because that ends up taking up most of the conversation. When they do finally talk about something else it is very short lived. My quick observation is that they lack well roundedness. I lose interest very quick and usually have to form a side conversation one on one with my husband.
On the other hand, knowing the psychology of relationships, it could lead to a loss of mystery. Some people need things out of their routine to keep a spark in their relationship. When you stop being curious about your partner and you think you know everything about them you may stop trying to be spontaneous and that can lead to living parallel lives. That may work for some people, they might feel content with it. It doesn't work for everyone.
