As for the pushrods, as noted by others that is strictly a time saving option. Considering the average price for a set of adjustable pushrods, versus $80 to $100 per hour labor charges, if you aren't having the rocker covers removed for any other reasons then the adjustables will save you a little on the total bill. Reliability wise, as was also noted by others, that depends mostly on the person installing them. One piece rods are inherently more reliable, and they are also lighter. Adjustables, if installed correctly, can be just as reliable and they offer the ability for fine tuning.
As for the lifters, it's not the hydraulic portion of the lifter you need to worry about. The part of a Harley lifter that usually fails is the roller, and quite often the first time most riders know they have a problem is when the roller bearing fails and trashes several other parts. A set costs a little over $100, I consider it cheap insurance.
Jerry