The 853 is what we have in my county's 4H shooting program, the kids shoot really well with it and I've found it to be accurate and free of problems so far after 7 years as the instructor. The only issue I have found is young or small shooters find it heavy and hard to charge. I've shot them quite a bit to sight them in so the youngsters can be close to the target.
It might be me but I have found the pellets made for the high velocity air rifles in .177 caliber don't shoot well, it might be they were just cheap ones but if memory serves me correct I don't think they cleared the bore, lead to hard maybe and causes too much drag?