I have sphericals throughout my suspension to take it further in stiffness but my car is track only and I live in Southern California where weather is mild. The big drawback is that they can corrode/wear so you need to maintain them, exposed bearings don't do well on street cars without constant maint.. Poly is a good choice for increased stiffness for street applications where you have to cope with weather and go to track on occasion.
note- I have many of the 034 sphericals along with tubular control front built with sphericals.
Also note that sphericals can wear MUCH quicker than poly or rubber, especially if used on the street.
