I'm a little late to the convo, but add me to the list of converts from 34/70 to S-189 for dry lager yeast. I find that it has a bit more character (i.e., a slight bit of sulfur production), and doesn't mute hop flavor as much as 34/70. I haven't noticed any improvement in time to bright beer over 34/70, but I don't think it takes any longer either.
The only downside to S-189 is that it doesn't seem to play well with warmer fermentation temps like 34/70 does. With a traditional lager fermentation temp, it is as good or better than 34/70 for all the lager styles I've tried with it. Not that 34/70 is a bad choice, but it doesn't add much and tends to scalp hop flavor.
TL;DR - If you have good temp control use S-189, otherwise use 34/70