Yes, if the bapt date in IGI was correct, then the death date in 1857 would also be correct (because day and month the same as IOM FHS or Brian's transcript).

It is always essential to double-check IGI or other transcribed entries in the actual parish register, or film of this. (Mat, these are widely available in NZ at LDS Family History Centres. See under Church of Jesus Christ of Latter Day Saints, in the phone book. Open to all.)

Sue