A couple of things ....
I've owned a Spoiler-Exploiter (actually my first Alembic), a Dragon's Wing, a tribute Spyder, and now my custom Series II Entwistle Replica Exploiter.
The biggest differences I noted between all of them was where the neck joined the body. On the Spoiler, it wasn't much of an issue in terms of playability, for me at least, because it was a 32 scale. On the DW and the Spyder, it was. The Spyder was probably the hardest for me to play - my arms aren't all that long, and my left arm was almost fully extended when on the first fret. Both the DW and Spyder had great tone, but the ergonomics just weren't for me.
Now, my Series II is a completely different animal. It is closer in shape to Entwistle's originals than the tributes are, and the body is moved up on the neck more, making it easier for me to play. The body is more pinched at the waist, and the wood back plates and truss rod covers make it far lighter. I also spec'd out a jazz bass like neck, which I prefer. And it's a Series II - the tonal possibilities are endless.
Here's a pic of me with it .....
Alan