I started out with the Urban ERT single point, because that was all he had at the time I bought my PS90 in Dec 2006. It was a nice sling.
He later came out with the 2 point, and I bought the extra attachments.
The 2 point is a lot better - get the 2 point. You can use it like a traditional sling over your shoulder, or hand the gun with the barrel pointed down, and the sling over your neck - This is the way to go. Then, it hands pointed down, but you aim the gun however you want, and it works great!