It’s easy for me to understand It doesnt have long paragraphs to explain one topic.
The method is a little bit same as Archangel of Magick by Damon Brand but the Sigil and Powers of an Angel is different. Also the Powers and Sigil are different.
Like the sigil and Powers of Vevaliah are these:
While in 72 Angels by Damon Brand are these:
Which one work fast result?
Of course the sigils are different. Each author created their own proprietary versions, and no one ever lists all the things a spirit can help you with so the fact that Whitespire differs from Brand in the powers of the angels doesn’t mean anything.
I haven’t used anything by Whitespire so I can’t speak to its efficacy, but if I remember correctly, @anon97554939 has, so she might be able to provide an answer.
I’ve not used Whitespire’s 72 angels, but it’s not uncommon to find different sigils and seals for angels and demons.
Take the Goetia for example and open Gordon Winterfield’s books versus Corwin Hagrove, or even S. Connolly or the sigils you find on google etc. If you start looking at demon grimoires, every single one has slightly different powers and abilities listed. If I were to write a book about my experiences, I wouldn’t use any of the known things either- because my experiences have been different from others, so I would use what I know rather than what others know.
If you trace Whitespire’s work backwards, you can actually find his real name (or maybe an original pen name) his patreon and information on how he develops his sigils. I have used all of his books except this one, and I’ve got so many on angels I can’t see any reason to purchase it- Same as I have many books on demons so I wouldn’t purchase a new one that wasn’t in kindle unlimited or anything, due to the fact I already have quite a few…
Basically, what I am getting at is Whitespire writes good material, he uses the same format for his seals in all of his books, regardless of which race of spirit we are talking about and his rituals are basically the same in each also, and his system works for everything else, so I would assume this work is as legit as Damon Brand’s, based on everything I’ve seen and I wouldn’t be swayed by the fact there’s differences as that’s pretty normal for grimoires by different authors.
If I wanted the exact same material, I sure wouldn’t by two books on one subject, but all of Whitespire’s other works have netted consistent results, so I wouldn’t shy away from this one, if I was interested in it personally.
Dr. Rudd’s sigils are different than that MS Sloane 3825. But the best source is Dr. Rudds i think.
You will have to test it for yourself and record your results!
The sigils and the workings are valid but it depends on you more than anything to make it work!
Tristan is an active member of the Gallery of Magick Facebook group. I tried one of his servitors without success but I was brand new to magic. Once he made a servitor so strong it apparently took on a life of its own and supposedly attacked someone. He destroyed it. He is adored by many in that group and has released many free sigils and instructions for use by members.
I recommend his Genie book if you want to start with something truly unique. That book even if you don’t ‘practice’ with it is worth its weight in gold as an encyclopedia.
I have several of Whitespires and Brands books, they are an good read 
