>I thought I used to be able to use the 'Online' dropdown to see a list of members currently on line.
>Is that a 'subscription only' option ?

There isn't a dropdown list for that. There is an option on the top toolbar. If it isn't there, I will, on an upcoming update, release it for all, as there is no specific need to have its configuration in the subscription page only.

Related items include the left side Online/Offline list of members, which you can configure when viewing someone's profile by enabling or disabling the related account to be visible in the Online/Offline area.