>> That's your personal preference wrt how much of the context should be 
>> left on the screen; it is well known that there are other preferences 
>> regarding this aspect.  Gregory's code provides the default Emacs 
>> experience of recentering, so it is the right default.  If we want to 
>> cater to other preferences, we need to make the 1st argument to 
>> recenter depend on scroll-related options, or maybe introduce a new 
>> user option.
>
> By popular demand, here is the patch, updated with a new option 
> 'isearch-motion-recenter', which defaults to t.
>
> (Note that you should wait to push it until my paperwork has been 
> processed by the FSF, I wasn't aware of that subtlety.)
>

And of course I forgot to attach "the patch".  Here it is.