Hmm…perhaps, though I’d push the date up a bit. There was a fiddle player from Donegal–can’t remember who now–who once talked in an interview about how people had once played an instrument called an fhidil cam (“the crooked fiddle”) before modern instruments were brought from Scotland in the 18th century. The fiddle did not really become all that widespread an instrument in either Scottish or Irish traditional music until the 18th century and the playing standards were not all that high until the end of the 18th century for Scottish music (a time period sometimes called “the golden age of the Scottish fiddle”) when you had collections like the Simon Fraser book and the Caledonian Repository, etc. and cracking compositions by Niel & Nathaniel Gow, James Mackintosh, and others all over the place. These tunes and collections were to have a tremendous impact on the development of both modern Scottish & Irish music and many Irish tunes–reels in particular–can be traced back to tunes published in these collections. It has been suggested that playing standards on the fiddle in Irish music were not all that high until after the Famine.
It is interesting that there isn’t more of a history of piob mhòr playing in the American South as there were pockets of Scottish Gaels in the region. Records of church services conducted in Scottish Gaelic go all the way up to 1929 in rural N. Carolina. Then again, pipes aren’t the easiest instruments to maintain and emigration probably didn’t occur in several waves as it did in Atlantic Canada which was helpful in replenishing the tradition there.
But yes, double stops=bagpipe drone effect. It is also interesting that the mixolydian mode, often a signature of older “classic” tunes in both Scottish & Irish music dates back not just to the piob mhòr, but the cláirseach, which apparently had a G mixolydian tuning. Many old jigs like Fraher’s and Humours of Ballyloughlin were probably remnants of piob mhòr and/or cláirseach tunes. The March of the King of Laois has been in recently confirmed as being the same tune as the Scottish piobaireachd Cumha Dhonnacha Mhic Rath (“Duncan MacRae of Kintail’s Lament”). Anyway, I seriously digress.
As far as impact of instruments goes, the impact of uilleann piping on flute technique has been pretty big. Prior to Matt Molloy, it wasn’t really done at all, apparently, now most everyone throws in the occasion cran or something into their flute playing.
I often wonder how the development of vamping accompaniment on the piano has changed the music. In Cape Breton, the simple style of piano backing that was quite common until about the 1960s or so was said to have developed directly from the rhythms of step dancing and the foot tapping patterns used by the musicians when playing. I would hazard a guess that the development of piano backing in Irish céili bands was less organic and more haphazard.