Hey Dan,
Glad to hear about the success you were having with Yotpo!
On top of automatically e-mailing your customers review requests, we let them write a review directly in that email--that's what gives us the best reviewer conversion rate in the business!
As far as SEO, Yotpo's reviews are crawlable and indexable by search engines and we'll soon have Rich Snippets available for Shopify users on our (very affordable) Premium plan. Existing users will get to keep Rich Snippets for free.
Thanks for the kind words about Yotpo!