While I'm still 10.5-11.5 (11.5 likely now, and I'll keep repeating this because even if I'm wrong I want to state my place as this is what I'm told), I will say this:
If PS5 comes out with more power than SX, that tf or so extra gain will not come cheap. It's not easy to push stuff that high, at all, and I imagine it will cost a pretty penny. It may only be an extra tf or so, but to get there requires a lot of cooling, reduces yields and all sorts of black magic. Not to mention the PS5 is already rumoured to have other parts that may cost more. But the gains are simply not worth it at all.
So there is a very good chance that there will be a bigger price gulf than we think between the two systems, that is, if it does indeed turn out to be higher.
Likewise though, the flipside is also true. If the PS5 happens to be slightly slower at 11.5, there's a possibility they can undercut the SX price and release cheaper. The losses over the SX in raw performance are tiny and barely worth mentioning.
We could very well be looking at an up to $100 difference here... crazy...