interesting, all of the familiarization courses I took when I was trying to become a range instructor said that it was a modified P226.
You are technically correct.
a modified P226. But it has it's own designation in the Sig catalog as the P228.
Sort of like the Glock 19 is a modified Glock 17.
I think it was an outgrowth of the original P226. I think other branches of the military liked the P226 and how it performed in the trials that eventually chose the Beretta M9 but they thought it was too big for their uses in P226 format. So Sig accomodated them and chopped it down to size.
I used to have one. While it is very similar to the P229 and size/shape, for some reason I liked it much better. It didn't feel like it was going to squeeze up out of my hand like the P229 always does.