I don't know what your conversion rate is from 'free' to 'premium' to 'pro', I'd definitely argue against these SaaS pricing 'expert' guidelines. $12/yr - $60/yr are what I like to call 'support the dev' pricing, hey I like your product and $12/yr is < less than a coffee a few times a year, $60/yr is a manageable expense for someone being a power user, $29/month is $348/yr, and while I see the benefit of your product I would never pay that for the features provided as a power user. And this is my problem with a lot of businesses they go from $0 to $15/month for their tiering, then $50/month, then "enterprise", for a product I like that I'm not using for business or something that I can't live without that's a hard sell ($10/month+).

Now the approach I might suggest would be raise premium to $2/month, if you buy for the year pay $12. Premium, $6/month, $60/yr. enterprise really depends on how an enterprise uses the product, but $50/month might be a little cheap, but again I really don't see the use case for an enterprise (>500 employees) for something like this.