Some people feel that slimline (and other) transmissions made in Taiwan are better than those from mainland China. Addressing only slimline, I don't see any difference in initial quality. I have manually tested up to 1000 from each place with very similar failure rates and failures from both places were better than I expected. I have not tested them for endurance.
I have not made similar comparisons with other styles of transmissions and I suspect if anyone has they are keeping the results to themselves. It is perhaps ironic but I seem to see more transmission failures showing up on here with higher priced (higher priced than slimline) transmissions. That is an ad hoc observation though not a acceptable way to determine failure rates.
In short, while you might want to watch them a little, I would not lose any sleep over the prospect of transmission failures - I doubt you will be getting a lot of pens back because of them. I seldom get calls to replace failed transmissions and some of the ones I do get the transmission was damaged by the turner..
