vCenter 5.5U2 to 6.2 - SSO/PSC

Hello,

I'm a bit confused here and the more a read into it, the more confused I get. A classic brain-fart, one could say...

So...we're running vCenter 5.5u2 and have the SSO component installed but not configured and do not actively use SSO. Now when moving to 6.2, do I have to use SSO/PSC or can I just let it upgrade but still continue to NOT use SSO/PSC?

Second question;

If I indeed have to use SSO/PSC, would I be better of enable SSO on our current 5.5 infrastructure or just upgrade to 6.2 with PSC and configure as I'm updating it?

Thanks.