If you've got any input, I appreciate it!
The problem with your requirements are that you're demanding that the bulk of your phone time is to be mobile, even though you don't need to be. Mobile telephony will always cost more than stationary, unless you try and shoehorn in mVoIP, then the quality just suffers that much more... and let's face it, mobile calling quality is already bad enough as is.
This means you need to make a judgment call. Which is more important to you: staying mobile during your calls, or saving money?
Just remember the iron triangle - Easy, Good, Cheap: Pick Two.
If you're talking for over 15 hours a month on the phone, I'm pretty sure call quality is going to be important.
If you choose mobility, you already know the price for that mobility, and you're already paying that ballpark. You could always switch to slightly nicer phones and GSM MVNOs to expand your communications options a bit with a smartphone, so you can get email if need be as you seem to be wanting to push towards that creature comfort for around the same amount per month. It'd also save you the hideous cash outlay that a hardware switch would require going to Republic, too...
If you'd rather save the money, first understand that at the usage levels you're looking at, you'll be shelling out around $15 a month between a VoIP home phone and a mobile (and that even goes for Republic after the taxes, by the way, only it's a $300 buy-in, zero customer support, and mVoIP calls off WiFi dependent upon the Sprint data network, which is worse than their voice coverage).
Point being, if you can stay with the plan you have and avoid any lifestyle inflation, you're not doing terribly... but you're also not far off from the best mobile rates you'll ever see for your usage patterns.
I noticed that Freedom Pop is expanding its options to cell coverage, although my concern is that they're currently extremely limited to metro areas--handy for my neck of the woods, but not if I travel at all (and I spend several weeks a year back with my family in extreme rural-land).
This is going to be a problem for any mVoIP solution, be it FreedomPop, Republic or TextNow. This is why I keep saying mVoIP is not mobile phone service... the call quality is worse, the functional reception coverage shrinks down to only the areas with high enough speed data and low enough latency to actually work, and they're all dependent primarily on the Sprint data network which has the smallest data footprint on the smallest mobile network in the nation with the highest congestion issues.