There's more to a bike than its weight.
Sure, the T-Line is the lightest. It's also ultra-niche. Who would go touring on a T-line?
I would argue that the weight difference is not significant unless it's the primary criterion.

Each bike has its own advantages and disadvantages.
You have to set your priorities and choose accordingly.
I tried the T-line, a great deception. The Birdy was much more satisfying. The Helix? If only there were more reviews.