Let me preface this by saying that I have been running for about 2 months now. I was once a good runner but that was 8-10 years ago and at the time I never used anything technological outside of a stop watch. I recently purchased a Garmin Forerunner 310XT and am now sifting through a statistical fog. Sounds like we are in the same boat. I have the foot pod and the heart rate monitor. Personally having the ability to breakdown my run statistically makes it more enjoyable for me as I can truly see improvements on paper. Training via heart rate is extremely confusing, I must have read roughly 20 different articles that say varying things. What I've deduced from these articles is if you maintain a heart rate in Zone 2 session after session of long durations you will eventually run respectable times in Zone 2. Also, Zone 2 being what it is, you will be able to sustain that pace for a very long time.
I'm going to take a leap of faith and believe that this works (Why not, something to try). Tonight was my first attempt at training in zone 2. I kept my heart rate between 125-158 BPM at all times. My average heart rate was 140, right in the middle of zone 2. The frustrating thing is that after an hour I had only traveled 3.66 miles. I continuously had to run and walk, run and walk in order to keep my heart rate in Zone 2. The positive is that I feel like I could go back out there right now. I could wake up tomorrow morning and log another 3.5 miles no problem. I could do 10 miles in Zone 2 if I had to. That to me is encouraging as I know I'll be able to log the miles I need to get to that next level.
Prior to this I was running the same as you were; For me, a 10 min/mile pace, avg heart rate around 180, the feeling that I wanted to quit after 15-20 mins followed by the feeling of I don't want to do this again tomorrow. The other downside is that the lactic acid that built up was causing me to be sore the following day.
On the flip side, back when I was in good shape (years ago), I started training by running as hard as I could. I had no method to this, no reasoning and no coaching. I started by running a timed mile each day as fast as I could. I'd run until I had to stop, walk a bit then run til I finished. I did this until I was running 1 mile in 6 minutes. I had no heart rate monitor and no technology of any kind outside of a timex. I never ran more than 1 mile and I never ran slow. One day I decided to run farther than 1 mile, I ran a 2 mile loop and felt so good I ran it again, I'll never forget it. I also ran it at a pace of about 7:30/mile. From then on I would run 3-5 miles non-stop at a strong pace. I dont recall as though my heart rate was low at any point during these runs. I simply feel that I could sustain my high heart rate for a much longer period of time because of my initial funky mile training and the fact that I always ran hard.
My point after all that is that I would trade the ability to sustain a high heart rate for 3-5 miles for the ability to run a 7:30/mile in zone 2, mile after mile. I'll be the test dumbie here unless you'd like to join me. If it doesnt work atleast I was sweating for an hour per day.
As I near closer to 30 I can tell you I have little desire to maintain a heart rate of 180 BPM, especially 5-6 times per week. I will mix in the occasional run in the higher zones. For now I'm looking to load it up in zone 2 and see what happens.