Are you a rotary flyer? A master's is a de facto requirement for helo TPS candidates right now, as HX-21 is only taking 2 pilots/yr for the foreseeable future, and there is no shortage of candidates with #1 EPs & MSs from quality (non-DL) programs. Not being snooty, those are just the facts of recent times (I got TPS in '12 w/o an MS)
If not, and you get into TPS, there are both Aero and Systems MS tracks at NPS (via DL) which provide many credits for the 48-wk TPS syllabus, so it may be wasted effort to start something before you know if you get TPS.
Most people I know who have completed the DL SE curriculum at NPS have been pleased with the overall workload, but frustrated by everything you'd expect from DL (minimal instructor interaction, low rigor, etc.)
Edit: a JO friend of mine translated his NPS DL SE MS into a job at Apple after his MSR was up, so it is valued.