The fellow who said that the Brooks Ghost would be a good replacement for the GT-2000 is just messing with you.
Comparable models from New Balance would include:
- 860v6 or 860v7 - NB's directly equivalent model. Slightly firmer and significantly more supportive than the GT-2000.
- Fresh Foam Vongo - Just as supportive as the GT-2000, but it does not feature a traditional medial post. Instead, the medial side of the shoe is "overstuffed," meaning that the cushioning is higher and firmer on one side than on the other. The Vongo isn't quite as squishy as the GT-2000, but it is also nicely cushioned.
- Vazee Prism - Not truly a directly comparable model, but it's an excellent option to explore. The Prism is as supportive as the GT-2000, but much firmer and more responsive.
I don't think most people would be comfortable doing all their runs in the 1500. I'd reserve it for speedwork and road racing. It's the best flat out there for those who require medial posting.
The closest competitors on the market would be Saucony's Fastwitch and Asics' GT Racer.