I don't have much on them yet and what I have isn't really verified very well except for the marriage. (Her name is Dinah or Dianna or Diana Allen by the way...not Sarah).
I have marriage intentions in Dartmouth on 16 Mar 1817 - that's documented.
And yes birthdates of 1796 or earlier is about right but I haven't found any sources yet with exact dates for either one of them. I have seen some death dates of 1867 and 1874 but so far have not found the death records that prove that out.