Spencer,
The way I understand it, if you have a basic (free) listing, a client who is not a subscriber to SOT will still be able to see your listing, but will not be able to get contact information from the site.  If they wished to contact you, they would have to look up your number manually. If the client has a subscription, they will have access to contact information for all listings, both enhanced and basic.   If you have an enhanced listing, anyone visiting the site can get your contact information whether they have a subscription or not.
The question of whether to purchase an enhanced listing or a subscription or both depends on how you use the site.  If you use the site soley to advertise your services, an enhanced listing would be the way to go.  If you use the site to find abstactors for your clients in areas you do not serve, and enjoy reading the content, the subscription would be the better choice.  If, like me, you use the site for both purposes, you would buy both.  My enhanced listing costs $129.00 a year for the seven counties I serve.  If  I get a couple of jobs a year out of it, I break even. Spending $99.00 a year for the subscription so I can help my clients and read the content seems quite reasonable, so I am doing both.
I really hope and expect that now that SOT is going to a subscription service, the content will continue to improve. Jarrod has written some great stuff in the short time he has been on board.  With Robert now having some money coming in, it should be easier for them to expand on the fine coverage we now receive for free.
Like everyone, I hate to write a check, but I think this is one of the easier choices I have.  I have found SOT to be the best thing for the abstracting community to come along in my thirty-plus years in the industry.