Re: NTD: Hipshot GB-7 D-Tuner
This depends on what music you most often play and in what tunings. If, for example, you play Metal in C#, chances are that you would set up your bass permanently in C# - bigger strings, greater neck relief, taller nut.
The D-Tuner isn't simply about extending the range downwards. It also introduces new playing possibilities. One-finger power chording whilst tapping in the high register. Sheehan stunts, bordering on Chapman Stick techniques.
I find that I play more creatively on four strings. It forces interesting moves around the fingerboard where a five string would only require a simple shift across by one string.