Grazing Study Findings: limit grass time or muzzle?

We have several horses that blimp out on our pastures.  One horse is now on permanent drylot with controlled hay due to metabolic issues.  Others have had their grazing time allotted depending on time of year/time of day and hoof issues.  Our owners are very savvy and gather and read and research all kinds of info trying to do whats best for each individual horse.  Then there are some horses, mine included, who are out on pasture as much as possible with no ill affects-so far. Well, except maybe for bugs this year....they are fierce, so finally ordered a fly sheet.  Don't know why I waited so long...
While reading a recent equine magazine, I came across an article about a study that was done in Britain on how limiting grazing time was affecting grass intake. From the article:

 " British researchers followed grass intake and grazing behavior in eight pony mares over six weeks. Four of the ponies had unlimited round-the-clock access to pasture, and the others had pasture access for just three hours a day.  The researchers estimated how much grass the ponies consumed by monitoring changes in their weight, and they used video footage to analyze their grazing behavior.
" The ponies in the restricted access group made the most of their limited time.  During the three hours when both groups were at pasture, they ate more grass than the others did.  And they adapted to the limited grazing schedule, they actually increased the amount of grass they consumed, from around 25 percent of their daily dry matter intake at the start of the study to about 40 percent during the final week"  (I thought that was amazing!  Smart ponies!)
"But the ponies weren't able to outsmart grazing muzzles,  In a second study, researchers monitored four ponies, measuring how much grass they ate with and without a muzzle over three hour periods.  Muzzles cut intake by more than 80 percent"
--research done by Biological, Environmental, and Rural Sciences, Aberystwyth University, Wales and presented at Equine Science Society Symposium last spring.

I just thought that it was fascinating that the ponies understood their time limit and actually ate more, a lot more, in a specific time period.   

The article goes on to state that grazing has benefits for most equines, but there are those that have a hard time processing the sugar and other carbs and they have to have grass limits.  The study suggests that grazing muzzles are a good alternative if it works for a particular horses situation.  Everything depends on the individual situation and horse, of course.