ALL of the sounds that you heard on the demo were most likely built off of a COSM bass sound (or two, since the
VB-99 has 2 COSM basses available per patch).
Think about the
VB-99 this way. There are the COSM bass and amp sounds. Those are triggered ONLY by the information sent via the Roland pickup. This is just a standard magnetic pickup that provides the
VB-99 with information from each string on your bass. In addition to the COSM bass and amp sounds, the
VB-99 has a bunch of effects based off of Boss and Roland pedals and rack units. Those effects can be used and accessed by plugging into the
VB-99 like you did. Again, most of the "magic" of the
VB-99 lies with the COSM basses and amp modeling. So, a preset that uses a COSM bass (or two) into a COSM amp model then through a reverb emulation will just sound like YOUR bass through a reverb pedal, since you aren't using the Roland pickup. For those purposes, a Boss GT-10B will be sufficient.
If you do plan to get the GK-3B, also look at the Roland GR-55. It has only 1 COSM bass model at a time but also comes with built in synth sounds. It requires the GK-3B but is significantly less expensive than the
VB-99 while providing some of the COSM fun. You might be able to get the GR-55 and the GK-3B both for less than the price you paid for the
VB-99. The
VB-99 is a fantastic unit but VERY deep and it takes a LOT of work to get it dialed in sometimes. It is not a plug and play device by any means.
Here's a thread on the new GR-55:
Roland GR-55 ( GK Guitar / Bass Synth plus Cosm Effector )
Here's the thread on the
VB-99:
Roland VB-99