Here's the blurb on I2-M438 from the ISOGG I Tree page:http://www.isogg.org/tree/ISOGG_HapgrpI.html
I2-M438 et al includes I2* which shows some membership from Armenia, Georgia and Turkey; I2a-P37.2, which is the most common form in the Balkans and Sardinia. I2a1-M26 is especially prevalent in Sardinia. I2b-M436 et al reaches its highest frequency along the northwest coast of continental Europe. I2b1-M223 et al occurs in Britain and northwest continental Europe. I2b1a-M284 occurs almost exclusively in Britain, so it apparently originated there and has probably been present for thousands of years.
I put the more relevant stuff in bold and underlined it.
Do you really think the non-R1b1b2 element in the north and east of Ireland is as high as 20-30%? I figured more like 10-20%, but I could be wrong.