I was a bit shocked by this question. I hadn’t thought of “success rate” before and naively I guess, didn’t know it was a “thing”. I expect 100% and get something way better than 99.9%
Don’t misread this as me saying the thing is perfect - clearly it’s not, BUT I have had two “proper” failed prints in over 3000 hrs of printing. They were both caused through heat creep, printing PLA on days when the the ambient temperature was over 30°c and I know now not to print PLA in the enclosure if I can’t moderate the temperature.
I have had the occasional frustration with first layer sticking issues, one just last night where I was printing a small disc with a different filament to the one I had been using. If you keep an eye on the first couple of layers all seems to go well after that.
FWIW even those issues are easy enough to overcome - I have a one layer “Z adjust” model that is about a 4" x1" strip. Using live adjust Z I simply change the Z height every half inch or so along the model as it’s printing and then it’s pretty easy to see what height it should be.
Clean the bed scrupulously with detergent and water, then it’s good to go until the next filament change. Mostly
Yep, I sound like a zealot (sorry about that) but my all round experience with both machine and company are so good that I even spend a small fortune on their filament occasionally, and don’t get me started on how good that is!