Well, thank you for that in-depth review of your phone. It seems you really do like it as your excitement shines through. The phone is one beast and I love mine as well.
I agree with everything you've pointed out, especially the capacitive buttons versus on-screen. I can't stand that the on-screen buttons aren't always visible so you have to think for a second about which one is where, and like you said...tap the screen to "wake" them first. It's a wasted step.
Overall, your experience has mirrored mine, however I use my phone MUCH harder than you do so I'm not getting the nearly 48 hours out of it. That said, it's miles above anything else, and even beats my former Droid MAXX and earlier Droid RAZR MAXX in battery life, even with the extremely high resolution and screaming processor.
I love that it's 64GB, and I know how everyone says, "yeah, but no removable SD Card slot...", so I'm here to tell you it's no big deal. I've added a couple attachments to make it even better for storage.
Below are three different USB OTG devices I purchased, all from eBay. The first is a multi-card reader - the most expensive at $8.54, works perfectly and although being a tiny bit bulkier than preferred (cord and all), it's a real neat device.
The second is a TINY, and I do mean TINY adapter (mine's in black). It's about the size of 4 chicklets, 2 end to end, and double-stacked. It's a double-ended dongle, so the end with the USB-A connector doubles as the MicroSD Card slot (and there's also a Blue LED inside to show activity), and the other end is the MicroUSB connector. It can go from the phone to the desktop or laptop or tablet in one quick remove and re-insert, and at $2.64 each it was what I consider to be a steal.
The third one is a novelty version of number 2, but with an added benefit of doubling as a charging cable (mine's blue and white). The "head" glows red when plugged in and flashes red when it's reading/writing. Both the number 2 and number 3 are small enough to be attached to my keychain by the tiny tethers. The number 2 didn't come with tethers, whereas the number 3 did, however at the ridiculously low price of $1.99 each, who's complaining?
With any one of these, you have solved the SD Card slot issue and it makes a great conversation piece as well. For me, I've found that
OTG Disk Explorer Lite - Android Apps on Google Play and
File Manager - Android Apps on Google Play both work nicely with them, however I like the interface of the latter one better.