BST looked good and was about to place an order before I saw that you're using spun content. I get that's its more cost-effective, but I don't get why you and countless others here persist in using it. Quality goes a long way and am sure many others (including me) wouldn't mind paying a bit more for it, especially for tier 1.
You also contradict yourself by saying "Is it automated? Nope. Every single link built in tier 1 is manually handmade" but then add "We write a few articles and then spin them using WordAi". So, which is it?
Third, I commend you for your 'results or refund approach'. I was tempted by this and feel it's a great addition and shows you have confidence in your work. Other sellers should take note. However, as courtesy, I should ask what your criteria for a 'serp rise' actually is - an improvement of 1 place? Would a +1 result after 3 weeks disqualify me from a refund?
Thanks & good luck.