I am no expert, and don't have personal experience with either rack. I have the same heel strike problem you do though, as I am the same height with size 13's also. The Jandd is going to be one of my next purchases. From looking at the Delta model I don't think that it will offer as much room to move the panniers back. For me one of the key features of the Jandd is the long section near the bottom that makes it easy for a variety of mounting positions. The only other racks I can find that offer that flexibility are even more expensive than the Jandd.
My current solution is a cheap one. I have a Blackburn Mtn-1 on my old moutain bike. I got some fairly large zip ties and used them for bag stops, just behind the vertical support on the rack. That keeps the bags back far enough to miss my heels. But the hook and bungee mounting system didn't like the off center mounting and the hook next to the zip tie would twist and the whole thing would come loose. The panniers are old and mediocre but the price was right (free) so I didn't mind messing with them. I just took the hook off one end and mounted it a little over an inch towards the rear. So far so good. The only drawback I have found is that the panniers are dedicated to use on one side of the bike only now.
The Jandd stuff is expensive (relatively) but they have always been good quality. Plus they used to make all of their products in the US, though that has changed some recently with their bags at least. I still think they make very solid designs that focus on practicality. One of my favorite Jandd products that I own is their nylon & velcro ankle strap. I have been using it for around 15 years and it is still going strong. I can adjust it with one hand while riding if necessary, the velcro is still good after all these years and the reflective material has stood up to scuffs very well. It was 4 or 5 times more expensive than the generic ones but has outlasted them by the same factor, and works better.