i incorporate an arch. ive run the gamut with different styles of benching. ive done from "to the neck" to a typical BB style bench press (elbows wide, flat back) to various styles of PL bench. i prefer my current PL style bench, not only because i plan to powerlift, but also because when going heavy on other styles, i would get shoulder pain. (the bad kind)
having changed my form, ive eliminated shoulder pain. as for chest development, its hard for me to tell. when i was bodybuilding i never weighed more than 185 before dieting down to 152 for a comp. back up to around 175 post comp. started incorporating OLY lifts and PL'ing. im sitting around 198.
my belief is that, since a PL'ers job is to lift more weight and continue to do so, alot of science with leverages and mechanical advantage is put to use. injury prevention is the key to longevity. i dont hear much about that in BB circles. IMO, minimizing wasted movement while recruiting the strongest muscles for the job is what PL'ing training is all about. what that means for the bench press is you will safely and progressively get stronger, overloading the core muscles involved in benching (chest, back, tri, shoulder). for those looking for strict isolation, they will reach a point where something else breaks down because one muscle gets too strong or the strain becomes too great without support from other muscle groups (case in point: shoulders on a elbows wide bench press).