Membership Premium Plugin migration to Membership Pro 2 plugin

Hi, I have a WP installation with the Membership Premium plugin at which has over 4600 members in it (and therefore significant revenue I dont want to interrupt. I want to move those members across to what will be their new site at with all their subscriptions, comments etc in tact and benefitting from the new system (which looks great by the way). I have already tried upgrading the Membership Premium plugin (which would be preferable) and having failed, therefore have created thinking I would be able to map the data onto the new plugin via SQL or something - but this is, as you'll know, impossible. What is the solution?

Thanks for your time in advance...