I agree with his stance and levels of experiencing spirit contact during evocation. I would like to add that within the levels, as he puts it, there are also sub-levels in each one. For instance in level three he says that the spirits are external to the magician's mind. But this can also happen on several sub levels. Lets say that S1 of 3 means that the magician sees a misty form of the spirit, but the other attendants in the ritual space can not. SL2 of 3 would mean in my opinion that the magician sees a fully complete form and the attendants in the space see perhaps a mist or shadow. SL3 of 3 would mean that all of them see/experience the same image of the spirit evoked.
And then Inominandum turns the topic from physical evocation into the actual practice of evocation. First let me state that I do not agree with his stance that the word "Tetragrammaton" on the wand was meant as a clue for the magician to write YHVH on the wand instead. If this were the case, why wouldn't they just write that. Clearly YHVH(even the form of Jehovah) is written-out in other grimoires of the same era. And the word "Tetragrammaton" itself is used in the text some grimoires of the conjurations themselves, which means that particular word was deemed as powerful in its self. Basically I don't buy into the theory that "blinds" were included into grimoires to throw off casual readers. That is such a victorian after-though to reconcile errors and or changes in various grimoire manuscripts.
Ok moving back to the topic. I do agree with Inominandum that there are currently different approaches to using evocation, and that it isn't necessary to have all the traditional tools, though the traditional tools do create more spirit activity(paraphrasing here).
Yes there are in fact different approaches to evocation and I will give my personal definitions to each practice below:
1st: The Traditionalist will go completely by the book(which ever grimoire he is using), and will not make any substitution or deletion in any tools, conjurations, and or curses.
2nd: The Modernist may either dispense with some of the traditional tools and combine the instructions of grimoire with massonic/lodge style occultism, or the modernist may in fact dispense with the book(which ever grimoire used) and lodge style altogether and just "wing" it in a minimalist style.
3rd: Then there is what I like to call the Via Media Magician. This VMM will more often than not go by the book, but is not afraid to make small tweaks and changes when needed. These tweaks and changes has nothing to do with laziness or short-cuts, but instead is based on a knowledge of what those elements being changed really mean and making appropriate alternatives using sound reason and logic.
For instance, when we look at Lemegeton's Goetia with its requirement of the lion skin belt, obviously there may be future magicians out there who will have no way of obtaining that. Afterall it is illegal to hunt lions in most countries(some countries allow for it but in unethical means), and the remaining antique lion skin rugs will eventually be gone or stored away in private collections.
So, a wise magician would break down what the lion-skin belt means, its associations, its practical aspects, and then formulate an equal alternative which s/he can use effectively in its place(making sure to stay within the spirit of the grimoire). That and I would say that a reasonable VMM would try to keep from making tweaks and changes if at all possible.
I would almost say that the Via Media Magician is probably even more traditional than the Traditionalists, because it is a fact that even the same grimoire(take your pick) had variations from one manuscript to another manuscript.