GTT makes a good torch, for sure. I work a lot of solid, and I can honestly say, GTT torches just make me happy. If you decide to go that route you might think about just biting the bullet and getting a Mirage and skip the intermediary stage of the Phantom. It never hurts to have that extra "oomph" on tap if needed... but read on...
Something to think about is the flame characteristics. Make sure you've spent some time on a Lynx or Phantom (or any other GTT triple mix torch) before buying GTT. The flame from a Nortel is going to be VERY different (less penetrating, heating a larger area more evenly) than a GTT torch and you may find yourself in the midst of a frustrating learning curve - particularly if you work hollow primarily. It's always beneficial to work on a few different torches, try a CC, try a Herbert Arnold, etc. prior to making a buying decision.
Do the research on various torches. For example, in your situation, it might be a good idea to consider the Red Rocket, rather than a GTT or even the RedMax. It will have similar characteristics to what you're used to while leaving you room to grow without needing to buy another torch.
These are my thoughts on your question, hope that helps
