I recommend you take Dana up on some lessons or his school.
I'll tell you why. I took his spey school a year and a half ago.
He does a great job, and it just isn't because of the school.
An example. Since I've known Dana, I think we have become friends to some extent. But I still consider him a casting instructor to myself as well. Anytime I dream up something spey, or have a question, I've fired off an email to him. Aside from his obligations as a Dad, Husband, Teacher/Guidance Counsellor, Angler, Conservationist, Kingfisher club member, and the many other fascets he takes up, he has always replied whenever he can find time and listened to my questions, and answered them as best as he could type trying to explain them in a way that I could best understand. And I view that as a committment from him to help make you (or in this case me) a better caster in the long run, not just at the school.
Also, there are a lot of casters out there. Many great instructors, pioneers if you will, who have helped develop this sport we all love (spey casting, spey fishing). I can put money down that there probably aren't many people anywhere near Dana in terms of knowledge and well roundedness of all things Spey. How many people are great long lined spey casters, and then can overnight change to fast action and the underhand method?
On a final point, don't confuse Spam, with the TRUTH! This is not a plug.
And I'll stand by my words. Take Dana up for 2 or 3 hours worth of private instruction. If you don't come out a better caster afterwards, or don't feel confident in what you learned and you being able to apply it to improving yourself, I will personally write you a cheque to reimburse you for half of your casting lesson. Keep in mind this offer is for you only.
I stand by my words.