Regarding Irish users I manage 3 kits on Ancestry and can view a 4th .
The first 3 are Irish ;
Kit 1 has 355 4th cousins or closer
Kit 2 (child of kit 1 ) has 516 4th cousins or closer
Kit 3 has 426 4th cousins or closer .
Vast bulk of all matches would be US based descendants of 1850 - 1950 emigrants from Ireland .
Kit 4 is US and has 756 4th cousins or closer .
Thanks noland, very interesting

. So if I take an average of those first 3 kits, it comes to
432 4th cousins or closer for Irish kits, just a little less than the current UK average of 448, probably, as you say, reflecting a lower number of testing overall in Ireland, but a higher number of US relatives descended from the vast wave of emigration which was much higher as a percentage of the population than GB. Is kit 4 a recent arrival to the US? It is quite a bit smaller than the
1661 average I have for two US kits of people of mostly pre 1840s US settlement.