True enough, but of all the things you might have to address, latency compensation is probably the easiest.
If a user’s feed is dependent on other users starring posts, then from the point of view of that user the subscription requirements are:
(1) Your followed users star/unstar posts.
(2) You follow new users.
(3) You un-follow users.
In all cases the publication needs to update reactively, but only in case (3) is there a potential for latency compensation - and you can only realistically use it if you know that removing a followed user affects your feed - and which posts within that feed.
I have had experience of the numtel:mysql package and the speed of reactivity is impressive: Most impressive features of Meteor to show in demos - #10 by robfallows
Yes - heard of it and seen a lot of interest from within the Meteor community. Also, @slava has been working on a full-stack Meteor implementation, which looks promising. However, I have no personal experience in it.