Bugs happen in software, you can not avoid. It is specially true for Vim which is used in wide variety of platforms. But still the segfaults bug listing is not that frequent as you described. Also Bram and other members are responding to to bug report in timely manner. Last I heard author of Sublime have stopped responding to bug reports.
Also you have zero knowledge of how Vimproc works. It spawns process or create socket connection in background and clients have access to it as a resource object from which client can read data during CursorMoved and CursorMovedI autocmd events. It is actually psudo-async but it works very well. I am using the plugins that have used Vimproc, even I used it in my PHP autocomplete plugin https://github.com/m2mdas/phpcomplete-extended (shameless plug) and it did not failed me yet. Also if you looked at the s:garbage_collect() method https://github.com/Shougo/vimproc.vim/blob/master/autoload/v... it is trying to release resource handles of the processes exited.
Also why should I need a clock inside vim? There is tmux/Screen status line for that. Please provide another valid use case.
That's right, you can update when there's user interaction. Great. Can you use that for remote pair programming? Nope. You'd only be able to see any updates if you yourself was typing. While every other editor can do that just fine.
When Vim is inactive, I can attach a function in a CursorHold autocmd event which would consists of loop that reads from the resource object and sleeps for a small interval after that. As the external program/socket connection is running in separate process, reading from it is not resource sensitive so it should not block Vim entirely.
BTW there is a plugin called CoVim https://github.com/FredKSchott/CoVim that implements pair-programming feature using default built-in Python binding.
Also you have zero knowledge of how Vimproc works. It spawns process or create socket connection in background and clients have access to it as a resource object from which client can read data during CursorMoved and CursorMovedI autocmd events. It is actually psudo-async but it works very well. I am using the plugins that have used Vimproc, even I used it in my PHP autocomplete plugin https://github.com/m2mdas/phpcomplete-extended (shameless plug) and it did not failed me yet. Also if you looked at the s:garbage_collect() method https://github.com/Shougo/vimproc.vim/blob/master/autoload/v... it is trying to release resource handles of the processes exited.
Also why should I need a clock inside vim? There is tmux/Screen status line for that. Please provide another valid use case.