The SIMS/Wal bass is an interesting piece. I will refer to it as the 'SimWal' now for ease of typing.
I understand it is being sold by Alberto Rigoni, who is an Italian bass journalist. I do think the price is really, really steep. I nearly fell off my chair when I saw that it was up for £8000 to start with. That is just a huge amount, even for something as undeniably unique as this bass. I do wonder what the original price was, and I hope it was nothing like the current asking, as I do not think that will be realised.
Where the wheel falls off for me is, it combines arguably the worst two aspects of both sides of this marriage of luthiers. It lacks the best bit of a Wal bass - the pickups and preamp - and is stuck with the worst part - the actual physical instrument. You will of course forgive me for saying so, as I like Wal basses but I'm the first to admit they can feel a little clunky and rudimentary. Then it is stuck with the SIMS Super Quad pickups. I find them to be pretty generic sounding and despite being undeniably flexible, I haven't heard a tone out of them that really makes me go 'wow' like many great basses with a unique or interesting voice do. I do like the sounds that Mark Smith gets out of his but that is the exception rather than the norm.
It's an interesting place to end up since when I first saw the Enfield Cannon basses years ago, I took them immediately to be very Wal-inspired, and that was a good thing when Wal was effectively finished as an ongoing concern at that time.