I didn't even notice that the pockets looked like an upside down heart in the photo. That was not on purpose at all and I would more then likely not put the beak that sticks up on the bottom of the pack again. It takes away from the capacity of the pocket.
I love using VX07 and VX21 together for my packs, VX07 works great for the tops and VX21 works great for the bottom of the packs.
I do like the top closure being the shock cord, cord lock and a clip, it is a very light setup for closing a pack. Getting the clip off can be a little challenging at times, but that just means that it is not going to accidentally come undone while hiking.
As for the pocket material, I responded to that post last week. Shane did a great list of pros and cons of the different materials and I would agree with what he wrote. I like using mesh and dyneema the best for pockets and in some cases Xpac, but find it a little stiff sometimes. If you know you are going to be bushwhacking through a brier patch on your hike then you would want to use a dyneema or xpac for the pockets, but if you are just going to be staying on trail then a mesh pocket will be great.
The one thing I love about building these packs is that there are no right or wrong answer or way to make them. You can do whatever you like, some ideas do turn out better then others, but you don't know until you try it. That is what I love about the MYOG forum, we all can share what we have come up with, which will give others ideas that they can build upon and share back with us. With each post and new pics of projects we all add fuel to the fire, so lets keep it burning!