I think that you will likely get better responses on the National Instruments forums for a question like this as the kind of company you are looking for is more likely to monitor conversations there. There are a couple of boards dedicated to job openings and developers looking for work.
http://forums.ni.com/t5/Special-Interest-Boards/ct-p/SpecialInterestAs for reliability you could confirm that the developers you pick are certified. NI maintains a list of names and contact info at
http://www.ni.com/services/certification.htm.
As with any certification not all good developers are certified and not all certified developers are good, but your chances are better with certified developers. If you are really concerned about reliability you can try a NI Alliance Partner.
