I tried the Luna Sandal but have mailed them back, what I did not like about them are 3 things:
1. The Leadville model (recommended for sierra-type trails) weighed in either 5.5 or 5.8 oz apiece versus the 4.5 oz Teva Mush Universal.
2. The thong design, along with the way the straps wrap around the ankle require the straps to be very tight to avoid having the rear strap fall off the ankle causing too much pressure between the big toe and the 2nd toe.
3. No matter how tight I made the straps, still the strap would fall off my foot/ankle at times. I wore them around the house for about 4 days. I'd bend down, squat (while packing food) and this would happen. I'd adjust the straps but nothing bullet proof.
4. The straps are not as slip proof as the velcro method used by Teva, it is more like a belt slip approach for straps. Some slippage can occur.
If Luna Sandal used the strap arrangement of Teva Mush Universal, I could see staying with the Luna Sandals for the 1 oz extra weight, as the sole is definitely more rugged (Vibram) and I'm sure less slippery when wet (per Robert's concern).
5. The Teva Mush Universal sandals are the most comfortable strap sandals I've ever put on my feet.