Easiest way to rooted stock 2.3.6 on SGS2 is to root 2.3.4 and then upgrade
I've seen a few questions on the forum asking how to root a 2.3.6 SGS2.
DooMLoRD's Easy Rooting Toolkit was a very easy way to root, without having to flash insecure kernels and all of that, and was great if the goal was just a rooted stock device. It was perfect for me, as all I wanted was AdFree, Titanium and OpenVPN on my device.
Unfortunately, the exploit the Easy Rooting Toolkit used seems to have been fixed in the SGS2 2.3.6 firmware and the toolkit doesn't work any more (see, for example, here
Before I upgraded from 2.3.4 I prepared myself to mess around with ODIN to get root back after upgrading.
Imagine my delight after upgrading (via OTA), that I still had root without doing anything at all!
So it looks as if upgrading a rooted 2.3.4 stock firmware to 2.3.6 results in a rooted stock 2.3.6 firmware (for I9100XWLA4, at least).
Which means that the easiest way to get to a rooted stock 2.3.6 SGS2 is to root it using DooMLoRD's toolkit before upgrading
Sorry if this is obvious and, if not, hope someone finds it useful.