Im losing unread posts.. deliberately not opening up posts only to find they are gone when I go back to "unreads"... I did have some 396 or so pages of these before the upgrade which have all gone... but im losing those I haven't read now..

Things are a bit different with the new version of SMF. The 'Show unread posts since your last visit' does exactly that now, it doesn't show all unread posts. There is a 'info bar' on that page that says 'click here to show ALL unread posts' which will show you the ones you're missing. I'll see if we can default it to that because I thought the same as you...