I usually play my silver flute, especially if I'm needing to keep up at a session, but also spend nearly as much time with my low and high whistles, my olwell bamboo flute, and some other keyless flute things as well.
My own Boehm flutes do not have holes in their keys, but I've occasionally borrowed a friend's whose flute does have open holes (when mine needed repair, etc). The first thing I tried was slides... I was so excited to try... aaaaand....
nope. Couldn't do it. After a bit got a LITTLE of it going but really nothing like certain People Of YouTube.
I can "slide" from A to B on my close-holed flute in a convincing enough way. Haven't figured out many tricks to accomplish much else yet.
Second, I am SUPER LAZY about how I hold my flute, which means that when I go to play a flute with holes, it's rough there for a while.

Third, as you probably know, one of the most obvious fingering differences between the Irish flute and Bohem flute is the way in which one achieves F#.
X X X X O O = F# on simple system D flute
X X X O O X = F# on Bohem system C flute (or XXXOXO)
This all well and good, except to my fingers, at this point, if they feel open holes underneath, they're automatically going to be giving me simple system fingerings and if they feel closed holes, they're going to give me bohem-system fingerings.
It's hard to unlearn that! #accidentalaccidentals