Is 'so I did', and other like expressions, at the end of a sentence good English?

Solution 1:

Yes, of course it is, but it's not normally found outside Ireland.

Solution 2:

These parentheticals, tacked on to the ends of sentences, have the same pragmatic role as the pragmatic markers (veridical / emphasising / focusing) truly or in truth or the facts of the matter are (which are, however, usually put before the matrix sentence).

As to their grammaticality, it's almost certain that a panel of professors of linguistics would pronounce them 'not ungrammatical'.

As to the advisability of using them, the effect they would produce outside Ireland would be to convince a listener that the speaker was either from Ireland, or affecting an Irish style of speaking. If the latter, this might be considered highly inappropriate.

"Correct"?

Solution 3:

As an Englishman from the Midlands of England, I certainly regard this as perfectly good English. I find the addition of 'so he did'; 'so I can' etc. at the end of a sentence to be fascinating - not least because of the fluency with which it is done. It must be quite difficult, because one has to instantly recap what one has just said in order to get the right verb/tense etc. Try it yourself - it's not as easy as those from Northern Ireland make it sound.