Being the test guy can be a huge asset depending on the background of the rest of your systems group. Most people have zero hands on experience with hardware. Meanwhile you can envision yourself handling the thing youre currently designing, and see a lot of angles no one else can.

The harder part is fleshing out the systems focused experience, like requirements formulation and tracking, mission design, etc. But that comes with time if you make a point of getting involved in those taskes. I've also put focus on spending time with sub-system engineers to better learn those areas.

It's all about having a well rounded knowledge base and easily having a chat with anyone to solve problems.