I'll add my £0.02 worth...
I've owned 5 Dolphin basses; 1989 Pro I (one of the first), 1990 Pro I, Set Neck Tone Chamber, Pro I 'custom shop' and a Pro II.
I presently own said Pro II and all others have been sold, that speaks volumes.
They share the Dolphin shape but the neck location, feel is superior (IMHO) on the Pro II. Added to which they are lighter and the Ash body maple neck sounds unlike any other variant. What is sometimes over looked is that the neck/horn position means the first position sits closer to you on a Pro II than a Pro I.
They do sound 'burpier' than the Pro I and you well never get the distinct tone of a NT Dolphin from one of these BO. One caveat is that the rear (bridge) pup solo is far to thin to be used in isolation, unless you are really trying to get that sound.
Footnote - the German 'Shadow' made basses 'v' the Japanese ones; I've yet to see or have a definitive way of identifying which is which... and I've done a fair bit of research over the last 30 years.
Great basses and not to be dismissed as an inferior Pro I, they are a distinct and different bass.