From what I've gathered on the web the 9mm barrels never swapped.
On the old full-size guns the barrels seemed to swap ok (from reports) between a Glock 22 and a SW40F.
There's a vid on youtube that shows a guy swapping a Glock 23 and a SW40VE barrel. The Sigma barrel worked in the Glock when manually cycling the slide (he didn't fire it), but with the Glock barrel in there the SW40VE slide wouldn't pull back.
Based on these reports I PERSONALLY wouldn't try it - and I'm personally really yearning for a .357 SIG barrel for my SD40VE but it's not worth trying IMHO. With them being as close as they are though I'm surprised none of the aftermarket companies have started making SD/Sigma barrels.
Also - unless that G19 barrel is threaded - I'm not sure what you're actually hoping to get from swapping the barrels. Swapping one 9mm barrel for another one doesn't seem very helpful.