Hi friend,
I have been using 89c55WD in place of 89c52 to get 20K flash(available in 55Wd),but i didn't get any problem so far.
only thing is I have not kept any external RESET ckt. in my application.Used the internal POWER ON RESET itself.
May be, this will help u.
let me know the result also.

bye
nvdeshpande@rediffmail.com