I know this post is pretty old but I thought I would add into this a little.
I have wondered about this very topic because I keep and breed cresteds. I have wanted to get into day geckos for a while and recently got some klemmeri. This was no problem because I am a dart frog breeder as well and make many culture of fruit flies a week as well as bean beetles, flour beetles, sprintails, and isopods. Now I can feed these little geckos my MRP and all these feeder insects. It works great and now I am getting a pair of l.williamsi as soon as I can.
To get back to the point I also will be getting some giant day gecko species soon...hopefully. I had wondered about feeding them mostly MRP because I only breed mealworms and want to keep the cricket bill low. I know we are talking very different things but as of right now my male crested eats only MRP. I can offer him bugs all day and he would never even consider. He is not fat by any means. He is slim trim and healthy. The female like the occasional mealworm/cricket but those are only offered once a week or so.
Since most of you seem to say MRP only is out of the question, would my females feeding regime be more feasable?