Wow, that's awesome job indeed.
I guess time will tell if VoLTE requires hardware chip or not. My reasoning was the fact that only LG revolution got that honor of first phone doing that while there are Tbolt, Charge that came out first with better recognized brand like HTC, Samsung.
Other than brand, what makes you prefer Tbolt than Revolution? To me Revolution is better on internal storage size, screen, battery and possibly camera. It also has HDMI out/mirroring that's not in Tbolt. Have you tested it yourself with Tbolt side by side on those things?