Changing Leo's diet- Advice needed

Ever since I got Leo- about a year ago- he's never been a hay eater. Suprise suprise his incisors didn't line up properly and he's had to have them removed. His molars have been fine *touches every wooden object in the house!!*. His poops aren't as good as his wifeybun's, Roxy. Hers are golden , but recently Leo's are getting more... moist.
He'll eat hay for a bit, then go off it. I get a new brand, same story. It's costing a fortune in hay... he's a bit keener on dried grass, but it certainly doesn't make up the 85% of his diet it should do.
So what I was thinking, was instead of this diet, could I attempt something a little more like the diet of a wild bun? IE gradually increase the amount of grass he eats until it makes up most of his diet (he loves grass!!) with a small amount of dandelions, plaintain (sp) etc and feed the normal few pellets and veg? I can't think of a reason that wouldn't work, as long as I changed it slowly. I would still provide hay and dried grass should he want to eat it, and for Roxy who likes it.
Any ideas or tips would be welcome! :wave:

Yep, it's fine to use fresh grass as the 'hay' portion of their diet.. better even as it's more natural. Like you say, you need to build up the quantity gradually as you would any new food but other than that no issues really

Joejoe wouldn't eat hay and for dental reasons the vet said he had to, or he too would have had to have had his big teeth out, and it turned out it was my fault really as i used to give him unlimited nuggets and he was filling up on them, when i severely restricted his nuggets down to a much much smaller amount surprise surprise he started wolfing down his hay, and luckily for him his toothy pegs were spared Definitely try cutting down on the nuggets, i did it overnight pretty much as it was an emergency but it probably is best to do it gradually if you can