Matej, since you have 8300 did you suffer from dust under screen? i had two 8300 both had started to collect dust after a week of use. Now i'm waiting for 8310 :D
Unfortunately my 8310 developed dust under the screen just like my 8300. Took a little longer, but it's there. I've just resolved myself to periodic take apart and cleaning. I don't use a case (only Invisible Shield on the screen) and it stays in my pocket FWIW.