Because the chainrings on a 4-arm spider have longer unsupported arcs than those on a 5-arm of the same BCD, they may well be slightly more susceptible to warping. After one of my admittedly somewhat heavy friends bent a TA Professional (3-bolt) chainring, he replaced the crankset with a 5-bolt Stronglight, and I put the TA set on my wife's bike, a much less demanding application.
The new 4-arm designs are yet another stupid fad foisted on the bike-buying public by the manufacturers, to render their 5-arm chainrings and spiders obsolete, and perhaps to save 20 percent on the cost of bolts. Simple physics tells us that, for a given total weight, a wheel with more spokes is stronger than one with fewer. On my mountain bike and road touring bike, I plan to stay with a 5-bolt 110/74mm system as long as I can.
The wonderful thing about standards, such as BCDs and bolt counts, is that there are so many from which to choose!