@Eduan - thanks for that link although that's more to do with PayPal admin and transferring accounts I think.
@Cristian - that's right. There are lots of nice goodies in the s2member framework alone without the payment systems, for example checking how many logins there are and from what IPs. It avoids having loads of plugins that may do the same thing but would not necessarily be integrated properly and anyway would fill up my dashboard.
Level #0 and level #1 is all I need but while #0 is by definition free, my question is how someone would 'register' themselves at level #1 (or how I would 'promote' them subject to various conditions). I could use a subscribe plugin as the completely free membership and then just #0 for what I want but I would rather differentiate between a casual visitor, an interested visitor and a member by using s2m.
I am using AmberPanther's WP Include File which enables me to do pretty nearly anything I want in posts, pages or widgets. (This is by far the neatest way to do this - I just have a library of php files that access $wpdb etc). So if it is just a matter of hacking some code, that's OK. It's knowing which s2m function to call and ensuring that the database is not compromised.
The registration for Level 1 appears to need a paypal payment which is what I want to get round ...
BTW the other membership plugins I have tried are the WPMUDEV Membership, which as an ugly registration page and the rather better Your Members plugin which wraps [private] round all your posts [/private] and only nods at categories and tags for membership level protection.