FANS
Yes the Archer is still in production, and are very well equipped and finished.
In my experience having operated both types, that is C 172 and PA28, the PA28 is cheaper to run
DON't OVERFILL
The new 172's are very nice, however I don't agree that Piper hasn't moved along as far as Cessna.
I'll think you'll find an Archers cruises faster than the C172, and for the same power settings the fuel burn is the same. Fuel injection is good but doesn't give better fuel consumption. With the faster cruise the Archer will have a better mpg than the Cessna.
True, fuel injection offers advantages so far as carb icing goes but then I've never had a carb ice problem when flying an Archer IFR. So far as hot starting goes I've seen many many people have problems hot starting an injected C172. The problem in most cases is incorrect technique but is still there just as it can be for poor technique on a carby engine.
STEEP TURN
I'd suggest the corrosion problems you talk of can apply to any aircraft not just Piper. Older Pipers were generally better corrosion proofed than the same vintage Cessnas. There's more than one or two Cessnas that have been abandoned dues to the costs of complying with the SIDS programme.
Your hail damage comment is hard to fathom. I don't see why the outcome should be any different based on the makers plate fitted to the airframe. Plus hail damage, no matter the aircraft type can be "repaired" just by filling the dents and repainting.