The A7II is the same sensor and ISO performance as the original A7, but with IBIS. I never shoot my A7 over 1200 because to my taste it gets ugly. I'd rather just use fast glass and keep the ISO down. All reports I have heard are ISO is not as good as the Q, but OK.http://www.dpreview.com/articles/9955093579/leica-sl-typ601-in-depth-camera-review/2
Doesn't look so good in comparison to pretty much anything of this generation, especially at ISO 3200 & 6400. Surprised at how well the A7II did in comparison.
Having seen the work DPR does with their review cameras for many years, I don't take them seriously any more.
I would guess SL ISO performance is similar to A7II. I don't hear rave reviews about A7r2 ISO either.
If the A7r2 was not hamstrung by a quirky sensor cover, highly variable native glass, poor batteries, poor RAWS, awful interface I would be more impressed with the pixel count. It does offer the ability to crop well into any image, and it's ahead of the SL without doubt in that department. Otherwise, for me, it's a paper tiger.
That's not to say I don't see great photography with all the Sonys here. I credit the shooters more than the gear.