The ergonomics argument doesn't hold water. I switched to a 20mm spaced sixer from a 17mm sixer in about a half hour. Trying to go back to the tighter spaced bass after a couple weeks was a different story. Sure I could've forced myself to go back to the tight spacing, but after finding how much less effort was involved with a wider spacing, why would I want to? Hell, I could do my morning jog in a three piece suit wearing clogs if I wanted to. Doesn't sound like fun though. If someone else likes it, great. IME tighter string spacing slows things down.
Seriously, G&L, don't drop what you already have. Just offer a wider spacing option five string. You don't have to offer the L-2500 wide here. Just try one bass with it. Maybe the JB in a five with 19mm?
edit: Heh. Someone beat me to the JB/SB idea before I hit post. Great minds...