I have used hundreds of Boge LR 510 and probably 50 or 60 Boge LR 808 cartos. In general they are all good cartos. The only major difference I have noticed is that the 808 will leak a little bit more from the battery end when full. That's just because there isn't as much of a collar to retain
juice. Performance wise they are pretty much the same.
Some people have been complaining lately that all Boge cartos have been lacking quality control and there is a bigger variance from 1 carto to the next. I have not noticed any increase in DOA cartos or any major variances but I order cartos pretty far in advance and I am still using cartos that I ordered in August. That is partly due to the fact that I have also been using the 1.7 LR, 1.5 dual coil and Echo-E cartos on a trial basis.
Hope that helps