The beverly is a beauty! I say GO FOR IT!! Don't worry about the patina, it doesn't happen so fast at all and if you don't use as an everyday bag it will take a l o n g time for it to get a patina let alone a dark patina. My mono speedy is super light still and I wear it maybe 2x a week for about 30 min. the two times I go out in a day, lol.
I also wanted to say, I consider mini lin a monogram bag, as it also has LV's on it and the fleurs and what not. So if you wore a mini lin in the past you were already wearing a monogram bag. I think it's more the vachetta that was turning you off and that's it's more mundane right? When you get a new mono LV, the vachetta is light, like white, and it then turns to a peach color when exposed to sun and light. It really won't happen so fast, I think it's a very slow process and if you don't use it everyday it won't even happen in that noticeable of a way. It certainly won't get dark unless it's your workhorse bag and you live in a hot and sunny climate.