I really like the NTL idea, and I definitely think you guys should push on with it. NTL could help bring more interest to Ultimate++ as well. Consider people starting using NTL for their own applications because of the runtime characteristics, and then later starts looking for a gui toolkit.
Actually, NTL was never standalone project. It was originally meant for more or less the purpose you suggest (to make "something" public quick and gain interest), but results were disappointing...
Complete U++ seems to have much better response in fact, even for NTL.