I don't like the Volquartsen skeletonized hammer, which is supposed to reduce lock time but may result in light primer strikes. They say it doesn't, but I prefer a standard (Mark II) hammer anyway.
I also don't like the profile of the Volquartsen trigger, as compared to the standard trigger. Actually, I use a Clark trigger on mine, which is like the Ruger trigger except that it's steel, with tighter tolerances.
You get something like 90% of the benefit of the Volquartsen kit from their sear alone, which is available separately for a fraction of the cost of the entire kit.