How do I set up free & paid subscriptions correctly?

Hi all!

I'm developing a site using WP 3.5.1, BP 1.7 and your membership plugin.

My intention is to have one free, and one paid subscription for new users to choose from on signup. I've tried all different kinds of setups to get this working – but so far without any luck.

This thread explains most of my problems: https://premium.wpmudev.org/forums/topic/sign-up-button-not-showing-for-upgrades

But I still post a new thread on this as I've got mixed answers on how to set this up properly (with or without any bugs):

As from what I could understand, Alexander Rohmann suggests I assign users to the free subscription as default on signup. But when I talked to Barry, he told me to leave this to none.

For me, it makes more sense to have it set to none (as the first thing users do is picking between free or paid). But now users don't get get assigned at all if they choose the free subscription.

Therefore, I tried setting the free subscription as default. Now the problem is the same as in the thread above. Also, users who choose the paid subscription get assigned to both free and paid.

I've tried using both PayPal Express and PayPal Single Payments Gateway, with the same result. Which suits my needs best?

Thanks!