After eating the same thing for five years, I wouldn't want to come off it, either! lol
When you look at the nutritional content of the muesli mixes, you lack from of the crucial nutrients, and the ever important protein and fibre, in the correct amounts.
I have heard from other rabbit owners that their buns HATED Supa Excel, but that other brands worked well.
I really do recommend a pellet feed, it's just the most balanced for their nutritional needs.
Also, if anyone here is switching to pellets, remember that rabbits' digestive systems are very sensitive. All switching should be done gradually. To go onto Excel, for example, you should be mixing it in, in greater and greater amounts, over 10 days. 10-14 days is a good guideline to introduce new staple feeds, my notes say here...
Not trying to get on anyone's nerves, especially as the newbie, just regurgitating my lecture notes!