Murfie3170, I'll be honest, I've never heard of a Sanibel trailer so I can't give any opinion on it. I do know that the Bighorn is now rated as a full time unit. We have a similar floorplan in our Landmark and love it. There is plenty of storage which is very important to us as full timers.
The Heartland Owners forum is also a great resource with many other owners willing to help with questions or issues.
Good luck with your choice.
2011 Heartland Landmark Grand Canyon