Meh, question might be would Regulars be better than the Black and Tans, I mean you're likely to have more "direct" combat but less of the Non Combat incidents.
I wouldn't be so sure if the public perception is the Irish are being supported by Germany.
Next point is that if you do get to that level of deployments/combat what happens to the Irish forces already deployed in WW1? There was concern within the British High Command following the Rising (and the Germans played it up), if you have a large Rising and larger British reaction would you see Irish Units taken off the line?
If the Irish units on the line remain “loyal” (ie no incidents against orders, violence amongst the unit, religious agitation, etc) then I’d imagine they’d be left there. Units left kicking their heels are more vulnerable to agitation or spreading dissent, whereas units in the line are more likely to maintain the ‘status quo’.
The last thing CIGS and the Army Council want is discontented Irish units heading back to Ireland.