Not really, the UniBass has a very natural guitar/8 string bass sound, the pitch shifter will always sound a bit more artificial. Plus the UniBass can also add a 4th between or 5th above the shifted note as well as an almost usable overdrive and tone control and has a split out for signal routing.
I happen to own both, and I can say that the akai is by far superior to the boss in generating a signal one octave above.
The GT-6b suffers from too much delay and other digital artefacts.
The Unibass sounds much more natural!
