The rev 17 and rev 21 instructions mentioned were written prior to the release of all the d2x versions. D2x in and of itself is a modification of waninkoko's cIOS rev 21. Now that 8 going on 9 revisions of this are out it has simply become known as d2x. As stated in the first post made about this issue, there are hermes cIOS in slots 222 and 223, versions 4.0 or 5.1 depending on what you installed. These are entirely different from d2x. The guide you are talking about said you can use either/or. Meaning you can use d2x cios OR hermes cIOS. Hermes cIOS are on versions 4.0 or 5.1. D2x is on version 8. Two different things.