Nice work! Genuinely creative; well produced; very atmospheric.
Both tracks certainly made me sit up and listen (well, I'm at work so sitting up is the norm, but you get what I mean...).
I mix on headphones too, so I'm aware of the limitations but you've done a good job on this. 'Phones are never ideal for mixing, sure, but just like monitors I think you can get to learn their different quirks and characteristics over time. Plus, it keeps the baby/neighbours happy, which works for me.
I personally recommend AKG headphones (http://www.akg.com/
). They're very affordable and offer a nicely flat response. A good alternative to more well known brands.