QWI quals
Beg to disagree slightly with courtney on his view that qwi is the best flying qual you can have. I know times have changed a bit, but in my view test pilot is still the best flying qual you can have. Most useful of all the fast jet test pilots were those who had worked as qwis first, but such overqualification is probably rare nowadays!
Agree entirely that it won't do your career any harm - I found it very worthwhile! Good luck!