for me, running a flat tappet gave three negatives in one summer, wiped out cams and the consenquences. After that rollers in my own use, some occasional harm either from own stupidity or from the parts getting tired. I think I have hade maybe ten lifter failures, a couple from wearing out and some others loosing pushrods etc. The cams may have gotten some scars, but nothing you can't fix yourslef. Some rocker failures too, the aluminum ones get tired if you stress them and break after a lot of cycles, just like aluminum rods. Our stuff has been relatively low rpm, so the weight is not a huge factor. Although the current one has a red line of 7700, it has been together for three summers without problems. Forgot a couple of hurt valvepsrings during this time, but since switching to endurance springs, there hasn't been any problems. In an old Hot Rod magazine they compared similar grinds on hyd flat tappet, solid flat tappet and roller designs. The roller won clearly, they produced a broader tq curve. And that's also the reason the OEM went with rollers; while having the cam adv. degrees low to meet emissions, you still get more area under the curve and retain, or increase the performance. Like I wrote before, there is an advantage, but is it worth the 1000 or so in your case is the hard question. You might spend it elsewhere for even bigger advantage. My next engine, a 340 W2, will most likely use a flat tappet because it's a budget build. We'll see wether the decision is right or wrong.