D'oh!
This is going to be embarrassing.
I recently started finding these sites after over 10 years of giving up on magic, give or take a few brief relapses. I was buying cards for my ever-growing collection this summer when one of the shops also named a couple of the learning sites.
At first, I kept a deck of blue Bicycles for my "home study" deck and put a pack of Bees bought from the Luxor in my laptop case, to tinker with at work. (I often have more privacy in the office than at home.)
Even in my ignorance, I could feel the difference. The Bicycles stayed where I put them, even with a child hanging off of one arm. The Luxor-bought Bees were a lot more slippery and more difficult to handle.
I don't know if you meant to ask whether anyone has experience using them or if anyone has found them useful. I have experience using them, but it wasn't that great.
In the future, I may very likely go back to them just for the challenge of learning to use more difficult cards. That day will only come after I feel a lot more comfortable performing the slights on regular Bicycles.