I wouldn't let the warranty issue hold me back because it's not like they're actually going to honor it.
You can return a defective firearm to most gun makers with a clear description of the problem and they'll usually either blame it on you or fire 2-3 shots, fail to duplicate the problem, and return it with a note saying that it's within factory specs. When they do try to fix it, they usually get it wrong and you end up sending it back several times. There will be little or no documentation of what they did or tried, and you probably won't get to talk to the same person more than once if you try to call them. Each trip can take months, and you can easily spend more on shipping than the gun is worth. You'll hear this story over and over on gun forums. 99% of the time it's cheaper and faster to sort out problems on your own.
I've owned a T3 Lite in 308 and a T3x Lite in 30-06. I can't say for sure, but I believe there's enough meat in those barrels to be threaded safely, especially if you cut them to 18-20".
Buy a T3 Lite, double up your ear pro, and shoot it for a while without the can. Bolt guns are pretty simple and problems in a new one tend to show up right away. Then you can play warranty roulette if you want. If nothing is wrong, then have it cut and threaded, and enjoy it.
Okie John