It depends, my metal fork is heavier than the plastics, thats a given, but it is light enough to be easy to use. I didn't check how many tines, but I can tell you this, I didn't get the ones with the cages on the sides. That makes the fork too heavy for metal and even worse if your stripping your stall to re-bed it.
I have about medium weight tines, the smaller ones bend and ding out of proportion, and the thick ones make the fork too heavy. I guess you just have to do a bit of shopping around and find one that works for you.
I played with mine in the store, I know it sounds silly, but I wanted to check it out. I put my coat on the floor, and pretended to scoop it up a few times, to see how it felt carrying weight. I found it nice and easy even though there was a coat on it, so I decided to buy it.