I have had both, not at the same time though.
The split coil Soapbars are a little fatter and wider sounding.
The J pups are perhaps more midrangy and focused.
I actually like the sound of the soaps with the bass EQ cut a little. It's more jagged sounding than the standard J's. Take all this with a grain of salt because this is based on my memory of the standard spacing Thumb.
IMO the 5 string Broadneck is the most comfy Warwick neck. It is a flattened U- shape which is thick but not overly so. Honestly, I don't know how I played the standard spacing for 9 years. Oh yeah, the broadneck balances better and is more comfy overall... To me!