You could do it, but have you ever handled a subcompact glock? You must adjust your grip to eject the mags. I have a G33 that I use the G32 mags with sleeve in and it won't drop the mags without relaxing my grip. I love the commander size of the G33 with the G32 mags, but if you're wanting a long barrel 17, I would cut it down to fit the 19 mags.
Yeah, I have a G27. Love the little pistol. I had a G19 but never carried it in summer clothes due to my thinking that the grip was too long and it stuck out like a sore thumb. If I could pick up a cheap police trade-in G22 I'd probably hack it up for the little mags.